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In the first of two papers we described the development in the field of allergy mechanisms as described by Clinical and Experimental Allergy in 2015. Experimental models of allergic disease, basic mechanisms, clinical mechanisms and allergens are all covered. A second paper will cover clinical aspects. [ABSTRACT FROM AUTHOR]

Background and objective Allergic contact dermatitis and its animal model, contact hypersensitivity (CHS), have long been documented as type 1 T-cell-predominant immune responses. Although type 1/type 2 T-cell deviation has been repeatedly demonstrated to play an important role in many human diseases and their animal models, the potential of tilting type 1/type 2 T-cell differentiation of CHS by modulating the manner of administration and dosage of hapten remains unexplored. This study examined the effect of these two factors on type 1/type 2 balance of CHS. Methods ELISA methods for detection of isotypes of hapten-specific antibodies and cytokine profiles of in vitro reactivation culture as well as ear-swelling assay were used to indicate type 1 or type 2 T-cell immune responses. Results In this paper, it was demonstrated that dosage of hapten has no effect on the type 1/type 2 T-cell balance of CHS, whereas epicutaneous administration of hapten through patch application could tilt the type 1/type 2 balance to decrease type 1 and to augment type 2 T-cell responses. Patch application-induced modulation is still effective in ever-sensitized mice and the augmented type 2 T-cell responses are persistent and increase progressively in strength after repeated immunizations. Moreover, it was demonstrated that the augmented type 2 T-cell response can downregulate the elicitation of CHS. The major mediating cells of the enhanced type 2 T-cell responses were determined to be CD4+ T cells (TH2 cells). Conclusions These data show that epicutaneous administration of hapten through patch application augments TH2 response which can downregulate the elicitation of murine CHS. This exploration may contribute to the understanding of regulatory mechanisms involved in contact allergy. [ABSTRACT FROM AUTHOR]

Background Variable results have been obtained when patients with atopic dermatitis (AD),) have been patch tested with allergens known to produce a positive prick lest. The significance of patch test results in our understanding of the pathogenesis of AD therefore remains questionable. Objective This study was designed to determine the relevance of either positive or negative patch test results in relation to the expression of cell mediated immunity to allergens in patients with AD. Methods Thirty-five patients with AD exhibiting patch test positivity to one or more aeroallergens on "tape stripped* areas of the back were retested without prior tape stripping. Nine patients again showed positivity to one or more allergens while 26 failed to show positive reactions. In six of the positive patients both positive and negative patch tests were observed. Skin biopsies were taken from these matched positive and negative patch test sites as well as from an area of uninvolved skin. Samples were frozen and cryostat sections were analysed with immunohistological techniques using monoclonal antibodies to investigate the distribution of immunocompetent cells. Results All positive patch tests exhibited characteristics of a cell mediated immune response. The negative patch test sites were also found to contain evidence of mononuclear cell infiltration. Both negative and positive patch test sites showed significantly greater proportions of T cells compared to uninvolved skin. No increase in numbers of RFDl positive and RFD7 positive macrophages were observed in either positive or negative patch test sites. Expression of CD23 by CDl positive Langerhans cells was raised in both negative and positive patch tests compared to uninvolved areas. A significant increase in the population (RFD7+, CD23+) was seen in positive patch test sites compared to uninvolved skin. An increase in the proportion of RFDl positive cells expressing CD23 was also seen in both negative and positive patch tests compared to uninvolved skin. Conclusions This paper demonstrates that immunological reactions are promoted at 'non-tape stripped' patch test sites where no clinical evidence of reactivity is seen. Together the data demonstrate that the presence of systemic cell mediated immunity to specific allergens identified in patients by positive patch test, may also be present when no clinical signs are seen at the patch test site. [ABSTRACT FROM AUTHOR]

Background Comparable T cell-containing and T cell-depleted culture systems for human IgE synthesis arc currently not available. Objective This has prompted us to develop peripheral blood mononuclear cell (PBMC) based culture systems for human IgE synthesis in the presence and absence of T cells. Methods In this paper we describe simplified conditions for in vitro synthesis of high levels of IgE by human peripheral blood B cells, both in T cell-containing cultures and in anti-CD40 stimulated T cell-depleted cultures. Results T cell-depleted cultures released approximately 20 times more IgE [range 4I0-2220ng/mL (mean 1270 ng/mL); based on six experiments using cells from three donors] than did T cell-containing cultures [range 23-105 ng/mL (mean 58ng/mL); based on 15 experiments using cells from three donors]. Reconstitution experiments were performed lo investigate the role of T cells on IgE synthesis. Adding T cells back to the anti-CD40 stimulated T cell-depleted cultures resulted in a dose-dependent inhibition of IgE production. In the absence of anti-CIMO low numbers of T cells stimulated, while high numbers suppressed, IgE production: the optimal ratio of T cells to non-T cells for maximal IgE production was found to be 1:1. At this ratio, irradiated (non-replicating) T cells supported a much greater IgE synthesis than did non-irradiated T cells. Conclusion The development of these systems provides directly comparable T cell-containing and T cell-depleted cultures for human IgE synthesis from peripheral blood, allowing further study of the role of T cells in IgE regulation. These systems will also be of use for determining whether potential modulators of IgE synthesis act on the T cells or on other cell types. [ABSTRACT FROM AUTHOR]

Background Selected cytokines produced by allergen specific CD4+ T cells from atopic individuals contribute to both the specific and non-specific effector mechanisms of the allergic immune response. The chemokine family of cytokines and tumour necrosis factor (TNF)-α are leucocyte regulatory and proinflammatory molecules. The chemokines include interleukin (IL)-8 and the RANTES/SIS cytokines. Objective There bas been no systematic survey of chemokine production in T-cell subtypes. Because of their wide range of biological properties, it might be expected that they would be closely regulated by T cells. This paper illustrates one way (through the characterization of T-cell clones) these questions might be addressed. Methods Northern blot analysis was used to quantitate steady state transcription of selected cytokine genes and enzyme linked immunosorbent assay (ELISA) was used to quantitate soluble product. Results mRNA expression of the chemokines (IL-8. HuMIP-lα and HuMIP-lβ) and TNFα is upregulated in TH2-like cloned house dust mite reactive human CD4+ T cells under conditions of activation and during the induction phase of anergy. Although the development of anergy superinduces mRNA for both IL-8 and TNFα, protein production is low compared with that released during activation. In contrast, RANTES, a chemoattractant for CD4+ /CD45RO+ memory T cells, eosinophils and basophils, is constitutively expressed at the RNA level by the T cells and not modulated by signals of activation and anergy induction. The production of IL-2, IL-4 and IL-5 mRNA and proteins during the induction of anergy peaks at 2h after stimulation, whereas the kinetics following activation of the T cells is delayed in comparison. Conclusion These data show that the induction of the anergic state coincides with post-transcriptional regulation of selected cytokine genes. Further study of these phenomena will impact on our understanding of the mechanisms of induction of anergy and the regulation of allergic immune responses in desensitization. [ABSTRACT FROM AUTHOR]

Background: Cannabinoids are lipid‐derived mediators with anti‐inflammatory properties in different diseases. WIN55212‐2, a non‐selective synthetic cannabinoid, reduces immediate anaphylactic reactions in a mouse model of peanut allergy, but its capacity to prevent peanut‐allergic sensitization and the underlying mechanisms remains largely unknown. Objective: To investigate the capacity of WIN55212‐2 to immunomodulate peanut‐stimulated human dendritic cells (DCs) and peanut‐allergic sensitization in mice. Methods: Surface markers and cytokines were quantified by flow cytometry, ELISA and qPCR in human monocyte‐derived DCs (hmoDCs) and T‐cell cocultures after stimulation with peanut alone or in the presence of WIN55212‐2. Mice were epicutaneously sensitized with peanut alone or peanut/WIN55212‐2. After peanut challenge, drop in body temperature, haematocrit, clinical symptoms, peanut‐specific antibodies in serum and FOXP3+ regulatory (Treg) cells in spleen and lymph nodes were quantified. Splenocytes were stimulated in vitro with peanut to analyse allergen‐specific T‐cell responses. Results: WIN55212‐2 reduced peanut‐induced hmoDC activation and promoted the generation of CD4+CD127−CD25+FOXP3+ Treg cells, while reducing the induction of IL‐5‐producing T cells. In vivo, WIN55212‐2 impaired the peanut‐induced migration of DCs to lymph nodes and their maturation. WIN55212‐2 significantly reduced the induction of peanut‐specific IgE and IgG1 antibodies in serum during epicutaneous peanut sensitization, reduced the clinical symptoms score upon peanut challenge and promoted the generation of allergen‐specific FOXP3+ Treg cells. Conclusions: The synthetic cannabinoid WIN55212‐2 interferes with peanut sensitization and promotes tolerogenic responses, which might well pave the way for the development of novel prophylactic and therapeutic strategies for peanut allergy. [ABSTRACT FROM AUTHOR]

Background: Characterising the clinical and immunological impact of daily cat exposure in cat‐allergic subjects with asthma who live with cats (WC) and those who do not (WoC) may provide understanding of the drivers of the allergic response. Methods: Clinical and immunological characteristics (skin prick test, spirometry, symptom assessments, immunological markers) were compared between asthmatic subjects WC (n = 10) and WoC (n = 9). Results: WC subjects had greater use of long‐acting beta agonists (p <.05) and high‐potency corticosteroids. No differences were observed in lung function, nasal and ocular symptoms, or asthma control between the groups. Cat dander‐ and Fel d 1‐specific IgG4 concentrations were higher in WC than WoC subjects (both p <.05). Total IgE and cat dander‐, Fel d 1‐ and Fel d 7‐specific IgE concentrations were similar, but Fel d 4‐sIgE was higher in WC subjects (p <.05) versus WoC. Basophil sensitivity to cat dander extract and Fel d 1 was lower in WC versus WoC subjects (p <.05) and correlated with higher IgG4 concentrations (r = 0.63; p =.009). Fel d 1‐specific CD4+ T‐cell responses polarised toward Th2A responses in WC versus WoC subjects; Fel d 1‐specific IgE correlated with surface expression of CRTH2 and CD200R (both p ≤.05). Conclusion: Immunological differences observed in WC versus WoC did not reflect clinical tolerance with natural cat exposure. The ability to live with a cat despite allergy could be driven by higher preventative medication use. This study may support design of novel therapeutics for allergy management. [ABSTRACT FROM AUTHOR]

The article presents information on the abstracts of the Annual Meeting of the British Society for Allergy and Clinical Immunology that was held at the East Midlands Conference Centre, Nottingham in July 1997. In the paper "T-Lymphocyte Adhesion to Nasal Polyp Endothelium," by F.A. Symon, C.A. McNulty and A.J. Wardlaw, the authors said that adhesion molecules have been widely implicated in the tissue specific homing of memory T-cells to the site at which they first encountered antigen. Despite being a major tertiary organ in lymphocyte re-circulation and a prime site for encountering airborne allergens, a homing adhesion receptor for the lung has yet to be defined.

The article examines the relationship between T cells and allergens. According to the author, T cell activation in allergy is not as clear as it was initially presumed. The author states that there is a global predisposition to allergy in atopic subjects attributed to deficient Treg cell machinery which allows the Th2 cell activation to occur in response to all antigens.

The article discusses various reports published within the issue, including one on a clinical trial of patients with birch pollen allergy, one on antenatal peanut exposure and one on T cells in allergy.

The article discusses various reports published within the issue, including one by Mehr and colleagues on the prediction of late-phase reaction in children with anaphylaxis, one by Shichijo and colleagues on the use of prostanoid DP1 antagonist in treating asthma and the study by Boudousquié and colleagues which demonstrates that the removal of a putative CD25 positive regulatory T cell results to the loss of tolerance to allergen.

Summary: Severe asthma in children is a debilitating condition that accounts for a disproportionately large health and economic burden of asthma. Reasons for the lack of a response to standard anti‐inflammatory therapies remain enigmatic. Work in the last decade has shed new light on the heterogeneous nature of asthma, and the varied immunopathologies of severe disease, which are leading to new treatment approaches for the individual patient. However, most studies to date that explored the immune landscape of the inflamed lower airways have focused on adults. T cells are pivotal to the inception and persistence of inflammatory processes in the diseased lungs, despite a contemporary shift in focus to immune events at the epithelial barrier. This article outlines current knowledge on the types of T cells and related cell types that are implicated in severe asthma. The potential for environmental exposures and other inflammatory cues to condition the immune environment of the lung in early life to favour pathogenic T cells and steroid resistance is discussed. The contributions of T cells and their cytokines to inflammatory processes and treatment resistance are also considered, with an emphasis on new observations in children that argue against conventional type 1 and type 2 T cell paradigms. Finally, the ability for new technologies to revolutionize our understanding of T cells in severe childhood asthma, and to guide future treatment strategies that could mitigate this disease, is highlighted. [ABSTRACT FROM AUTHOR]

Background Timothy grass ( TG) pollen is a common seasonal airborne allergen associated with symptoms ranging from mild rhinitis to severe asthma. Objective The aim of this study was to characterize changes in TG-specific T cell responses as a function of seasonality. Methods Peripheral blood mononuclear cells ( PBMCs) obtained from allergic individuals and non-allergic controls, either during the pollen season or out of season, were stimulated with either TG extract or a pool of previously identified immunodominant antigenic regions. Results PBMCs from allergic subjects exhibit higher IL-5 and IL-10 responses in season than when collected out of season. In the case of non-allergic subjects, as expected we observed lower IL-5 responses and robust production of IFN-γ compared to allergic individuals. Strikingly, non-allergic donors exhibited an opposing pattern, with decreased immune reactivity in season. The broad down-regulation in non-allergic donors indicates that healthy individuals are not oblivious to allergen exposure, but rather react with an active modulation of responses following the antigenic stimulus provided during the pollen season. Transcriptomic analysis of allergen-specific T cells defined genes modulated in concomitance with the allergen exposure and inhibition of responses in non-allergic donors. Conclusion and Clinical Relevance Magnitude and functionality of T helper cell responses differ substantially in season vs. out of season in allergic and non-allergic subjects. The results indicate the specific and opposing modulation of immune responses following the antigenic stimulation during the pollen season. This seasonal modulation reflects the enactment of specific molecular programmes associated with health and allergic disease. [ABSTRACT FROM AUTHOR]

Background Although specific immunotherapy is the only aetiological treatment for allergic disorders, the underlying mechanisms are not fully understood. Specific immunotherapy induces changes in lymphocyte Th subsets from Th2 to Th1/Treg. Whether differences in immunological patterns underlie patient response to immunotherapy has not yet been established. Objectives We studied the immunological changes occurring during a 1-year period of Dermatophagoides pteronyssinus ( DP) immunotherapy and their relation with clinical outcome. Methods We included 34 patients with DP allergy who received subcutaneous specific immunotherapy ( SCIT) for 1 year. Following treatment, patients were classified as responders or non-responders. Fourteen allergic subjects who did not receive SCIT were included as controls. Peripheral blood was obtained at 0, 1, 3, 6 and 12 months and cultured with nDer p 1. Phenotypic changes, cytokine production and basophil response were analysed by flow cytometry; transcription factors were measured by mRNA quantification. Serum immunoglobulin levels were also measured. Results After 1 year of SCIT, 82% of cases showed improved symptoms (responders). Although increases in sIgG4 were observed, BAT reactivity was not modified in these patients. Increases in T- BET/ FOXP3 as well as nDer p 1-specific Th1/Treg frequencies were also observed, along with a decrease in Th2, Th9 and Th17. These changes corresponded to changes in cytokine levels. Conclusion Patients who respond well to DP- SCIT show immunological differences compared to non-responders. In responders, basal differences include a lower frequency of Th1 and higher frequencies of Th2, Th9 and Th17 cells. After 1 year of treatment, an increased production of sIgG4 was observed in responders, along with a change in Th2 response towards Th1/Treg. [ABSTRACT FROM AUTHOR]

Background Seasonal allergic rhinitis is a chronic inflammation in the nasal mucosa triggered by inhaled aeroallergens. The inflammatory reaction is controlled by allergen-specific T cells, but where and how these T cells become activated is not fully understood. Objectives We wanted to determine whether allergen-specific T-helper (Th) 2 cells are residing in the nasal mucosa under steady-state conditions outside of the pollen season and, if so, whether these cells are activated locally in response to allergen challenge. Methods Mucosal biopsies from the lower turbinate were obtained out of season from patients with either birch- or grass-pollen-allergic rhinitis and from healthy controls. Cultured explant samples were challenged with relevant pollen extract or with a mix of overlapping 20-mer peptides derived from the sequence of the major birch allergen, Betula verrucosa (Bet v) 1. After 24 h, culture medium was harvested for multiplex cytokine and tryptase analysis. Results Significant amounts of interleukin ( IL)-5 were secreted from resident cells in response to ex vivo allergen challenge in the allergic group only. No increase was observed for the other cytokines measured. Production of IL-5 in response to both extract and the Bet v1-derived peptide mix strongly suggested that T cells were a major source of IL-5. Conclusion Our explant model indicated that local presentation of antigen to resident allergen-specific Th2 cells is the early event in the pathogenesis of allergic rhinitis. These findings identify possible cellular targets for anti-inflammatory treatment. [ABSTRACT FROM AUTHOR]

Allergen immunotherapy (AIT) has been practised since 1911 and remains the only therapy proven to modify the natural history of allergic diseases. Although efficacious in carefully selected individuals, the currently licensed whole allergen extracts retain the risk of IgE-mediated adverse events, including anaphylaxis and occasionally death. This together with the need for prolonged treatment regimens results in poor patient adherence. The central role of the T cell in orchestrating the immune response to allergen informs the choice of T cell targeted therapies for down-regulation of aberrant allergic responses. Carefully mapped short synthetic peptides that contain the dominant T cell epitopes of major allergens and bind to a diverse array of HLA class II alleles, can be delivered intradermally into non-inflamed skin to induce sustained clinical and immunological tolerance. The short peptides from allergenic proteins are unable to cross-link IgE and possess minimal inflammatory potential. Systematic progress has been made from in vitro human models of allergen T cell epitope-based peptide anergy in the early 1990s, through proof-of-concept murine allergy models and early human trials with longer peptides, to the current randomized, double-blind, placebo-controlled clinical trials with the potential new class of synthetic short immune-regulatory T cell epitope peptide therapies. Sustained efficacy with few adverse events is being reported for cat, house dust mite and grass pollen allergy after only a short course of treatment. Underlying immunological mechanisms remain to be fully delineated but anergy, deletion, immune deviation and Treg induction all seem contributory to successful outcomes, with changes in IgG4 apparently less important compared to conventional AIT. T cell epitope peptide therapy is promising a safe and effective new class of specific treatment for allergy, enabling wider application even for more severe allergic diseases. [ABSTRACT FROM AUTHOR]

Background The suppressive mechanism of regulatory T cells (Tregs) has remained incompletely clarified. Recent studies found that CD39 expressed by Tregs may participate in the immunoregulatory role of Tregs. CD39-induced ATP hydrolysis and/or adenosine generation contribute to the suppressive mechanism of Tregs. Previous studies suggested that ATP is involved in allergic airway inflammation by acting on type 2 purinergic (P2) receptors, but the role of CD39 and CD39+Tregs in allergic airway inflammation has not been elaborated. Objective To investigate the role and underlying mechanism of CD39 expression by Tregs in allergic airway inflammation. Methods A model of allergic asthma was developed with ovalbumin--alum in female Cd39 wild type (Cd39+/+) and deficient (Cd39-/-) C57BL/6 mice. Foxp3-GFP knock-in Cd39+/+ and Cd39-/- mice were used to sort CD4+GFP+ cells (Tregs) for exploring the role of CD39 expression by Tregs in allergic asthma. The effects of modulating CD39 activity with ARL67156 (inhibitor) or apyrase were also observed. Results ARL67156 greatly worsened airway inflammation including increased lung inflammatory cells infiltration, goblet cell hyperplasia, and higher levels of Th2 and Th17 cytokines in bronchoalveolar lavage fluid (BALF), accompanied by an increment in transcription factor (GATA-3 and RORct) and P2R (P2Y2, P2Y4 and P2Y6) mRNA expression in lungs. This potentiating effect was rescued by intratracheal injection of apyrase. Airway inflammation was markedly increased in Cd39-/- mice compared to Cd39+/+ mice. In contrast to CD39-Tregs, CD39+Tregs showed stronger suppressive effects on airway inflammation. In vitro suppression assay suggested that CD39+Tregs have more potent suppressive effect on cytokines secretion from CD4+CD25- responder T cells and the inhibitory effects were reduced by addition of adenosine A2A receptor antagonist. Conclusion CD39 expressed on Tregs participates in the regulation of limiting allergic airway inflammation by regulating extracellular ATP and/or adenosine. CD39 may represent a new therapeutic target for asthma. [ABSTRACT FROM AUTHOR]

Allergic rhinitis ( AR) and chronic rhinosinusitis ( CRS) are two widely prevalent inflammatory diseases in the upper airways. T cell immunity has been suggested to play an important pathogenic role in many chronic inflammatory diseases including inflammatory upper airway diseases. Inappropriate CD4+ T cell responses, especially the dysregulation of the Th1/Th2 balance leading to excessive Th1 or Th2 cell activation, have been associated with allergic rhinitis and chronic rhinosinusitis. Nevertheless, recent studies suggest that IL-17A and IL-17A-producing Th17 cell subset, a distinct pro-inflammatory CD4+ T cell lineage, may also play an important role in the pathophysiology of inflammatory upper airway diseases. Th17 cells may promote both eosinophilic and neutrophilic inflammation in AR and CRS. In addition, a few, but accumulating evidence shows that the Th17 responses can be tightly regulated by endogenous and exogenous substances in the context of AR and CRS. This review discusses recent advances in our understanding of the expression and function of the Th17 response and its regulation in inflammatory upper airway diseases, and the perspective for future investigation and clinical utility. [ABSTRACT FROM AUTHOR]

Background Several studies investigated whether hydrolysed proteins can induce tolerance to cow's milk ( CM) in children at risk of developing CM allergy. Due to methodological problems and inconsistent findings, the evidence for a tolerogenic effect is limited. A major problem is that different hydrolysates may give different outcomes due to variations in their production and composition. Objective The aim of the study was to investigate the effect of the degree of hydrolysis on the allergenicity and immunogenicity of whey hydrolysates. Methods The hydrolysis of whey was stopped at different time-points between 1 and 60 min. In 18 CM allergic patients, the allergenicity of the hydrolysates was determined by immunoblot and the basophil activation test. To test immunogenicity, CM-specific T cell lines were generated. Results In most patients, increasing time of hydrolysis decreased Ig E recognition and basophil activation. However, in five patients, hydrolysed proteins induced more basophil activation than non-hydrolysed proteins. The immunoblot data indicated that these patients recognized either a 25- to 30-kDa degradation product of casein or a 10-kDa degradation product of whey. Although T cell activation was decreased in all patients over time, half of them still showed a positive response to the proteins after 60 min of hydrolysis. Conclusion Increasing the time of hydrolysis reduces both allergenicity and immunogenicity of whey hydrolysates in most but not all patients. This indicates that not the degree of hydrolysis is decisive but the presence and stability of Ig E and T cell epitopes in the hydrolysate recognized by individual patients. [ABSTRACT FROM AUTHOR]

In this article the author focuses on a study conducted by researcher S.J. Wilson and colleagues related to the relationship between eosinophilia and airway remodelling in asthmatics. It states that patients with tissue eosinophils phenotype had increased epithelial damage, T cells and eosinophils in airway smooth muscle (ASM). It highlights that tissue eosinophils modify structural airway remodelling in asthmatics.

The article presents abstracts on medical topics which were presented at the 2012 annual meeting of the British Society for Allergy and Clinical Immunology, including one about the distinct patterns of neutrophils, another about the association between grass pollen sublingual immunotherapy and T cells, and another about patient reported outcome measures (PROMs) for asthma and allergy.

An introduction is presented in which the guest editor discusses various reports within the issue on topics including the increase of regulatory T cells in the nasal mucosa in rhinitis, symptom markers in individuals with cat allergic rhinitis, and oral allergy syndrome.

Background Subcutaneous specific immunotherapy ( SCIT) has proven sustained clinical efficacy against allergy. The recommended regimen for SCIT is a gradual updosing over a period of weeks. Commonly, in commercial products for SCIT, the specific allergen is formulated with an adjuvant, most often in the form of aluminium hydroxide ( AlOH). It has been shown that allergen-specific IgG antibodies are induced as a result of successful SIT. Objective To investigate the possibility of optimizing the formulation of AlOH-based grass-pollen allergy vaccines for SCIT in a way that allows for shorter updosing regimens while maintaining the immunogenicity of the vaccine. Methods Mice were immunized with various concentrations of Phleum pratense ( Phl p) allergen extract and AlOH or a fixed dilution of the maintenance doses of one conventional and one alternatively formulated vaccine. The kinetics of Phl p-specific IgG antibody responses in serum and spleen T cell responses were determined. Allergenicity, measured as the ability of the formulations to activate human basophils, was also determined. In addition, human T cell responses and the expression of dendritic cell surface markers after vaccine challenge in vitro were analysed. Results Specific IgG antibody responses were shown to depend on the AlOH concentration, but not on the allergen concentrations. The immunogenicity of the conventional formulation and the alternative formulation was shown to be similar with regard to the in vivo-induced IgG and T cell responses. In contrast, the allergenicity of the alternative formulation was significantly reduced compared with the conventional formulation. Conclusion The optimization of the formulation allows for administration of a lower dose of allergen while maintaining the immunogenicity of the product and at the same time reducing allergenicity. Clinical Relevance This study indicates that the optimization of the allergen and the adjuvant formulation could benefit the safety/efficacy profile and allow for shorter updosing. [ABSTRACT FROM AUTHOR]

Summary Background Accumulating evidence suggests that T cells play an important role in the pathogenesis of atopic dermatitis (AD); yet, little is known of the differentiation status of CD4+ T cells specific for common environmental allergens, such as the major cat allergen, Fel d 1. Objective To determine the frequency, differentiation phenotype and function of circulating Fel d 1-specific CD4+ T cells in adult individuals with severe persistent AD in comparison with healthy controls. Methods Using HLA class II tetrameric complexes based on a HLA-DPB1*0401-restricted Fel d 1 epitope, ex vivo and cultured T cell frequency and phenotype were analysed in individuals with AD and healthy controls. Cytokine secretion was measured by ex vivo and cultured IL-4 and IFN-γ ELISpots. Results Ex vivo Fel d 1-specific DPB1*0401-restricted CD4+ T cells in both atopics and non-atopics express high levels of CCR7, CD62L, CD27 and CD28, placing the cells largely within the central memory subgroup. However, the functional phenotype was distinct, with greater IL-4 production from the cells derived from atopics, which correlated with disease severity. Conclusions and Clinical Relevance Circulating Fel d 1-specific DPB1*0401-restricted CD4+ T cells in both atopic and non-atopic donors maintain a central memory phenotype; however in atopics, the cells had greater Th2 effector function, compatible with a disease model of altered antigen delivery in atopic individuals. Cite this as: L. R. Crack, H. W. Chan, T. McPherson and G. S. Ogg, Clinical & Experimental Allergy, 2011 (41) 1555-1567. [ABSTRACT FROM AUTHOR]

It has been suggested that Foxp3 regulatory T (Treg) cells inhibit allergic inflammation in humans by suppressing the activation of allergen-specific effector T cells. Whether this occurs at the site of allergen exposure has not been determined. To determine the occurrence of Foxp3 Treg cells in the nasal mucosa of allergic rhinitis (AR) patients and non-allergic controls after a nasal allergen challenge. Pollen-allergic patients ( n=18) and non-allergic volunteers ( n=7) were challenged locally with pollen extract or placebo for 7 days outside the pollen season. Mucosal biopsies were obtained from the inferior turbinate on days 0, 1 and 7 and subjected to multi-colour immunofluorescence and blood was drawn for eosinophil counts on days 0, 2, 5 and 7. Only AR patients receiving pollen extract experienced typical allergic symptoms and demonstrated increased levels of eosinophils in peripheral blood and nasal mucosa. In allergic patients, a transient early increase (day 1) in CD3 T cells was observed in the nasal mucosa, followed by a significant increase of Foxp3 T cells at day 7. No changes were found in the control group. The majority of Foxp3 cells co-expressed CTLA-4, CD25 and CD4, and a substantial fraction expressed the proliferation marker Ki67. Experimentally induced inflammation in AR patients leads to an early inflammatory response followed by accumulation of Foxp3 T cells in the nasal mucosa. Our findings are similar to that observed in allergic airways of experimental mice, which suggest that Treg cells are operative in allergic upper airway inflammation. It should be explored whether Treg cells accumulating in the nasal mucosa could be targets for therapeutic intervention. Cite this as: I. Skrindo, C. Scheel, F.-E. Johansen and F. L. Jahnsen, Clinical & Experimental Allergy, 2011 (41) 954-962. [ABSTRACT FROM AUTHOR]

Cite this as: C. A. Pérez Novo, M. Jedrzejczak-Czechowicz, A. Lewandowska-Polak, C. Claeys, G. Holtappels, P. Van Cauwenberge, M. L. Kowalski and C. Bachert, Clinical & Experimental Allergy, 2010 (40) 1323–1332. Background Staphylococcal superantigens may modulate airway inflammatory disease. Objective We assessed the effect of Staphylococcus aureus enterotoxin B (SEB) on T cell activation in patients with nasal polyps and asthma, and its possible link to aspirin hypersensitivity. Methods Leucocytes were isolated from five healthy subjects (controls), five asthmatics with nasal polyps without (NP-ATA) and five with aspirin-induced asthma (NP-AIA). Cells were incubated with increasing concentrations of SEB for 4 and 18 h. Release of TH1/TH2 cytokines was assessed by Cytometric Bead-Array. Foxp3 and TNFRS18-L expression were analysed by qPCR and flow cytometry. Results After 4 and 18 h, SEB significantly increased IFN-gamma, IL-4, TNF-alpha, IL-5 and IL-2 concentrations in supernatants of both NP polyp groups compared with controls. Baseline Foxp3 was significantly decreased in both NP-asthma groups. Incubation with SEB for 4 h induced a limited up-regulation of Foxp3 in NP-AIA patients, which was switched off consecutively. Foxp3 was significantly up-regulated in the control group after 18 h, but not in the NP-asthmatic groups. In parallel, TNFRS18-L mRNA significantly increased after 18 h in the NP-asthma groups compared with control subjects. This molecule was highly expressed in CD11c+CD14+ cells and its levels increased after 18 and 24 h culture in the NP-asthma patients. Conclusion SEB induces both TH1 and TH2 pro-inflammatory responses in patients with nasal polyps and asthma regardless of the presence of aspirin hypersensitivity. The nature of this response may be linked to a basal deficiency of Foxp3 observed in the NP-asthmatic patients and/or to the up-regulation of TNFRS18-L on monocytes/dendritic cell precursors. [ABSTRACT FROM AUTHOR]

Background Trials with probiotic lactic acid bacteria have yielded different results, which may be due to the strains used. Lactobacilli and bifidobacteria are known to be potent modulators of the immune system. The capacity of these bacteria used as probiotics to influence both T helper type 1 (Th1)- and Th2-mediated diseases has been shown before. However, the ability of strains to induce forkhead box P3 (FOXP3+) expressing regulatory T cells has not yet been investigated. Objective Test the inherent differences between strains in their capacity to induce functional regulatory T cells in human peripheral blood mononuclear cells (PBMC). Methods Human PBMC were co-cultured in vitro with either Bifidobacterium lactis W51, Lactobacillus acidophilus W55 or Lactobacillus plantarum W62 or an Escherichia coli control strain. The percentage of FOXP3+ cells, the origin of the induced cells and the functionality of these cells were assessed. Results Probiotic strains differ in their capacity to induce regulatory T cells. FOXP3+ cells were induced from CD25− cells and were able to suppress effector T cells. Naturally occurring regulatory T cells were not affected by co-culture with lactobacilli. IL-10 concentrations found in the supernatant showed a trend towards the same differences between strains. Blockade of IL-10 did not influence the up-regulation of FOXP3. No differences between lactic acid bacteria were found in IL-17, IFN-γ or IL-13. Conclusions Some probiotic strains are potent inducers of regulatory cells, while others are not. The clear differences between strains imply that an in vitro characterization of probiotic strains before application is recommended. Cite this as: S. de Roock, M. van Elk, M. E. A. van Dijk, H. M. Timmerman, G. T. Rijkers, B. J. Prakken, M. O. Hoekstra and I. M. de Kleer, Clinical & Experimental Allergy, 2010 (40) 103–110. [ABSTRACT FROM AUTHOR]

Cite this as: L. N. Fink, Clinical & Experimental Allergy, 2010 (40) 5–8. [ABSTRACT FROM AUTHOR]

Background Regulatory T cells (Tregs) are key players in controlling the development of airway inflammation. However, their role in the mechanisms leading to tolerance in established allergic asthma is unclear. Objective To examine the role of Tregs in tolerance induction in a murine model of asthma. Methods Ovalbumin (OVA) sensitized asthmatic mice were depleted or not of CD25+ T cells by anti-CD25 PC61 monoclonal antibody (mAb) before intranasal treatment (INT) with OVA, then challenged with OVA aerosol. To further evaluate the respective regulatory activity of CD4+CD25+ and CD4+CD25− T cells, both T cell subsets were transferred from tolerized or non-tolerized animals to asthmatic recipients. Bronchoalveolar lavage fluid (BALF), T cell proliferation and cytokine secretion were examined. Results Intranasal treatment with OVA led to increased levels of IL-10, TGF-β and IL-17 in lung homogenates, inhibition of eosinophil recruitment into the BALF and antigen specific T cell hyporesponsiveness. CD4+CD25+Foxp3+ T cells were markedly upregulated in lungs and suppressed in vitro and in vivo OVA-specific T cell responses. Depletion of CD25+ cells before OVA INT severely hampered tolerance induction as indicated by a strong recruitment of eosinophils into BALF and a vigorous T cell response to OVA upon challenge. However, the transfer of CD4+CD25− T cells not only suppressed antigen specific T cell responsiveness but also significantly reduced eosinophil recruitment as opposed to CD4+CD25+ T cells. As compared with control mice, a significantly higher proportion of CD4+CD25− T cells from OVA treated mice expressed mTGF-β. Conclusion Both CD4+CD25+ and CD4+CD25− T cells appear to be essential to tolerance induction. The relationship between both subsets and the mechanisms of their regulatory activity will have to be further analyzed. [ABSTRACT FROM AUTHOR]

Allergic diseases are rare in areas with high helminth parasite exposure and common where helminth exposure is lacking or significantly reduced, such as urban areas of developing countries and industrialized nations. Studies suggest that helminths induce a systemic immuno-modulatory network, including regulatory T cells and anti-inflammatory IL-10, which might play a key role in the protection against the allergic phenotype. Here, we review the current cross-sectional, birth cohort, and intervention study evidence for a protective effect of helminth infection on allergy. There is increasing evidence for a causal relationship between helminth infection and reduced skin prick test responsiveness to allergens. Cross-sectional studies have shown a consistent negative relationship, and these results have been confirmed in several, although not all, intervention studies. The immunological basis for this protective effect is less clear. Recent studies do not support the mast-cell IgE saturation hypothesis, but suggest that protection is associated with IL-10 production. As for allergic disease, cross-sectional studies support a negative relationship between clinical asthma and infection with some helminth species, particularly hookworm, but more studies are required to draw conclusions for eczema and rhinitis. In addition, none of the few intervention studies to date have demonstrated an increase in clinical allergy after helminth treatment, and further studies are needed. Furthermore, we are only beginning to understand the host genetic factors that are potentially involved. A genetically predetermined T-helper type 2 cell-dominated cytokine milieu reduces parasite burden and may enhance host survival in an environment where helminth parasites are prevalent. Lack of parasite exposure in such hosts might lead to hypersensitivity to seemingly minor environmental allergen stimuli. Large birth cohort studies in helminth-endemic areas that use epidemiological, genetic, and immunological tools are required to further examine how helminth parasites affect the development of atopy and allergic disease. Intervention studies with hookworm in parasite-naïve allergic individuals are currently ongoing in the United Kingdom to test the above hypotheses further. [ABSTRACT FROM AUTHOR]

The author reflects on the increase prevalence rate of food allergy in children. The author discusses the potential of oral tolerance as an efficient mechanism against food allergy, the prognosis of childhood food allergy, and the biomarkers associated with food allergy such as skin prick test, basophil activation, and food allergen stimulation. The author also mentioned other mechanisms for the condition such as active regulation by Tregs, clonal deletion, and anergy of T-cells.

Background Sublingual immunotherapy (SLIT) has been established in humans as a safe and efficacious treatment for type I respiratory allergies. Objective In this study, we compared three Toll-like receptor (TLR) 2 ligands (Pam3CSK4, Porphyromonas gingivalis lipopolysaccharide and lipoteichoic acid) as potential adjuvants for sublingual allergy vaccines. Methods These molecules were tested in co-cultures of adjuvant-pre-treated dendritic cells (DCs) with murine naïve CD4+ T lymphocytes. Patterns of cytokine production, phenotype, proliferation and gene expression were analysed by ELISA, cytofluorometry and quantitative PCR, respectively. TLR2 ligands were subsequently tested in a model of SLIT in BALB/c mice sensitized with ovalbumin (OVA). Results Among the three TLR2 ligands tested, the synthetic lipopeptide Pam3CSK4 is the most potent inducer of IL-12p35 and IL-10 gene expression in murine bone marrow-derived DCs, as well as in purified oral myeloid DCs. Only Pam3CSK4-treated DCs induce IFN-γ and IL-10 secretion by naïve CD4+ T cells. Sublingual administration of Pam3CSK4 together with the antigen in BALB/c mice sensitized to OVA decreases airway hyperresponsiveness as well as OVA-specific T-helper type 2 (Th2) responses in cervical lymph nodes dramatically. Conclusion Pam3CSK4 induces Th1/regulatory T cell responses, and as such, is a valid candidate adjuvant for sublingual allergy vaccines. [ABSTRACT FROM AUTHOR]

Background It has been suggested that allergic diseases are caused by defective suppression of allergen-specific Th2 cells by CD4+CD25+ regulatory T cells. However, such studies have been hampered by the difficulty in distinguishing regulatory T cells from CD25-expressing activated T cells. Recently, it was shown that conventional T cells expressed high levels of CD127, whereas regulatory T cells were CD127lo, allowing discrimination between these distinct T cell subpopulations. Objective The aim of this study was to study whether the putative regulatory subset defined as CD4+CD25+CD127lo was involved in grass pollen-reactive T cell responses. Methods Peripheral blood mononuclear cells (PBMCs) were obtained from allergic donors and non-atopic controls out of season. Grass pollen-induced cytokine production and proliferation were compared in cultures of undepleted cells and cells depleted of CD4+CD25+, CD4+CD25+CD127hi or CD4+CD25+CD127lo T cells. Results Undepleted cell cultures from allergic patients showed significantly increased proliferation and Th2 cytokine production compared with non-atopic controls. Depletion of all CD25+ T cells did not increase cytokine production or proliferation, and more importantly, no increase in Th2 cytokine production or proliferation was observed in cell cultures depleted of CD4+CD25+CD127lo cells (putative regulatory T cells) compared with undepleted PBMCs in both the allergic and the non-atopic group. Conclusion Our study showed that T cells from grass pollen-allergic patients and non-atopic controls responded very differently to grass pollen extract, but this difference could not be explained by differences in regulatory T cell function. Further studies are needed to understand the importance of regulatory T cells in allergy. [ABSTRACT FROM AUTHOR]

Background Characterization of T cell epitopes restricted by common HLA alleles is a powerful tool in the understanding of the immune responses to allergens and for the identification of potential peptides for future peptide immunotherapy (PIT). One important requirement is the identification and use of peptides that will bind to HLA molecules covering a large proportion of the population. Objective To identify commonly recognized CD4+ T cell epitopes in Fel d 1, restricted through frequently expressed HLA molecules for potential future use in PIT. Methods HLA matched antigen presenting cells, HLA blocking antibodies, and peptide truncations were used in ELISpot assays to establish HLA-restricted T cell epitopes. Cytokine responses were measured by ex vivo and cultured IFN-γ, IL-4, and IL-10 ELISpots. Results Responses to an immunodominant region of chain 2 were identified in the majority of atopic individuals and epitopes restricted by HLA-DQB1*06 and -DPB1*0401 were characterized in detail. Significantly higher ex vivo IL-4 and lower IFN-γ responses were observed to both epitopes in individuals with atopic dermatitis (AD) compared with those without disease. IL-10 responses were significantly lower in those with AD in the individuals with HLA-DPB1*0401. Conclusions We have identified an immunodominant region of Fel d 1 which is frequently recognized by CD4+ T cells from atopic individuals and contains epitopes that are restricted by very common HLA alleles. [ABSTRACT FROM AUTHOR]

Background The pathogenesis of IgE-mediated allergic disease is closely related to the production of T-helper type 2 (Th2) cytokines, which lead to IgE production pivotal for activation of mast cells and basophils. Proliferating T cells along with eosinophils expanded and attracted by Th2 cytokines are major contributors to the late-phase reaction. The activation of these Th2 cells is strongly enhanced by CD23-mediated IgE facilitated allergen presentation (FAP). Objective The present study aims to investigate the effect of specific immunotherapy (SIT)-induced allergen-specific non-IgE antibodies (blocking antibodies) on IgE binding to allergen, histamine release (HR) and CD23-mediated allergen uptake in antigen-presenting cells. Methods Competition between IgE and non-IgE for allergen binding was studied by Advia Centaur antibody measurements, passively sensitized basophils were used to study HR and IgE-facilitated binding of allergen to B cells (FAP) was studied by flow cytometry. FAP measurements were performed both with and without the addition of a reference IgE serum, which was included to obtain optimal complex formation. The serum samples were obtained from birch pollen immunotherapy ( n=21) or placebo control patients ( n=21) before and after 1 and 2 years of treatment. Results Statistically significant reduction of all parameters investigated was observed after 1 year of treatment and the effect was maintained during the second year of treatment. There was a clear correlation between the two FAP measurements and between each of them and the level of T cell activation reported upon previously. Moreover, strong correlations were found between changes in FAP, IgE binding and HR. Conclusion The present study clearly demonstrates that SIT induces changes in the composition of serum antibodies that inhibit IgE binding, HR and FAP to a similar extent. This suggests that these measurements, individually or in combination, may be used to monitor the immunological effect of SIT, even though direct correlations to changes in clinical parameters could not be demonstrated. [ABSTRACT FROM AUTHOR]

Background Chemical haptens induce both contact and allergic respiratory disease with dendritic cells (DCs) controlling and directing immune responses in vivo. Contact and respiratory haptens may promote differential cytokine production yet distinguishing these effects in vitro remains difficult due to human donor variability. Objective We sought to determine the effect of atopic status on the ability of DC to respond to contact and respiratory sensitizer treatment in vitro as DC from atopic donors are believed to promote Th2-type responses. Methods Enriched DC from control or atopic donors were treated for 4 h with levels of the contact sensitizer 2,4-dinitrochlorobenzene (DNCB) or the respiratory sensitizer trimellitic anhydride (TMA) that did not reduce cell viability. A sensitive intracellular detection technique was used to measure cytokine production, while T cell responses were assessed in a mixed leucocyte reaction. Results DC from control, non-atopic, donors produced cytokines differentially in response to sensitizer treatment; DNCB treatment significantly increased the production of Th1 cytokines IL-12 and IFN-γ while TMA induced the production of IL-13. Control donor DC treated with TMA stimulated less in a mixed leucocyte reaction than untreated cells with any response reduced further by blocking IL-13 in culture. However, DC from atopic donors showed no significant alteration in either cytokine production or T cell stimulatory capacity after sensitizer treatment. Conclusion Haptens modulate DC by changing the production of cytokines that may play a role in T cell stimulation and subsequent polarization of the immune response. DC from atopic donors were unresponsive to chemical sensitizer treatment, and may be deficient in inducing divergent T cell responses. [ABSTRACT FROM AUTHOR]

Background Specific immunotherapy (SIT) is the only treatment producing lasting clinical improvement in patients with allergy. We investigated the long-term effect of SIT treatment on the expression of chemokines: eotaxin, RANTES (regulated upon activation, normal T cell expressed and secreted) and thymus and activation-regulated chemokine (TARC), and their receptors CCR3 and CCR4 in biopsies of nasal mucosa from birch-allergic individuals. Methods Sixteen patients who completed a 3-year treatment programme 3–5 years ago, and 12 untreated, matched controls were included in the study. Patients recorded symptoms and use of rescue medication before and during the pollen season. Nasal mucosa samples obtained before and during the season were stained for eosinophil and mast cell markers and for eotaxin, RANTES, TARC, CCR3 and CCR4. Results During the pollen season, rhinoconjunctivitis symptoms increased in both SIT and control groups ( P=0.001 and 0.002, respectively). However, SIT patients had 37% fewer symptoms than controls. Medication use increased in both groups ( P=0.002) during the season but the SIT group used 28% less than the controls ( P=0.02). The number of eosinophils in the nasal mucosa increased in the control group ( P=0.01) and the difference between the groups was significant during the season ( P=0.01). No seasonal increase in the numbers of mast cells was seen, but during the pollen season, more ( P=0.02) AA+ cells were found in the controls than in the SIT group. The number of eotaxin+ and RANTES+ cells increased in the control group ( P=0.01 and 0.03, respectively) and the difference between groups during the season was significant ( P=0.01 and 0.01, respectively). The TARC+ cell numbers were lower in the SIT group during the season ( P=0.003). The CCR3+ cells increased only in the control group during the pollen season and remained unchanged in SIT patients, while CCR4+ cell numbers increased in both the control ( P=0.03) and SIT ( P=0.02) groups. Conclusion This study confirmed that decreased numbers of eosinophils in the nasal mucosa is a long-lasting effect of birch SIT. SIT also prevented seasonal rises in the number of cells expressing the chemokines eotaxin and RANTES. [ABSTRACT FROM AUTHOR]

Objective We aim to find what is the relationship between B cell antibody responses and specific T cell help in the specific cases of allergy and tolerance to peanuts. Background B cell antibody responses to foreign proteins usually depend upon antigen-specific T cell help. However, specific antibody levels can sometimes be maintained lifelong after infections or vaccination. Methods We measured peanut-specific proliferation and antibody levels in peanut-allergic and non-allergic children using tritiated thymidine incorporation and UniCAP, respectively. We also investigated the corresponding tetanus toxoid specific responses in both groups. Results We found that tetanus-specific IgG did not correlate with lymphocyte proliferation (Spearman rank correlation coefficient r′=0.08, P=0.74) nor with tetanus-specific cytokine production (IFN-γ: r′=0.198, P=0.285; TNF-α: r′=0.274, P=0.146; IL-4: r′=−0.007, P=0.96; P=0.221; IL-13: r′=0.363, P=0.056). Conversely, in peanut-allergic donors, peanut-specific IgE (average 21 kU/L, median 2.27 kU/L, range 0.34-100 kU/L) but not peanut-specific IgG was positively correlated with proliferation ( r′=0.751, P=0.003). In these donors, specific IgE was positively correlated with peanut-specific Th2 cytokines production: r′=0.635, P=0.02 for IL-4 and r′=0.641, P=0.025 for IL-13 and negatively correlated with Th1 cytokines ( r′=−0.71, P=0.007 for IFN-γ and r′=−0.746, P=0.005 for TNF-α, respectively). However, peanut-specific IgE was not correlated with T cell proliferation or cytokine production in non-allergic individuals. In conclusion, in allergic individuals, B and T cell responses to peanut antigens are correlated whereas normal immune responses B and T cell responses are uncoupled. Conclusion Our results support the view that B cell responses to allergens but not those to non-allergenic proteins are correlated with specific T cell responses and therefore specific immunotherapy targeting of such T cells would inhibit allergen-specific B cells. [ABSTRACT FROM AUTHOR]

Background β-Lactam (BL) antibiotics can induce non-immediate skin reactions, frequently manifested as exanthema or urticaria. The time between drug intake and the reaction appearance is generally 24–48 h. Because the mechanisms involved are not completely understood, diagnostic tests for these reactions have still to be fully validated. Objective To evaluate the role of skin and drug provocation tests (DPTs) in the diagnosis of patients with non-immediate reactions to BL. Methods We evaluated a group of 22 patients who developed maculopapular exanthema or urticarial exanthema after BL intake. Diagnosis was confirmed by DPT with BL. Intradermal/patch testing was performed with benzylpenicilloyl, minor determinant mixture, amoxicillin (AX), ampicillin (AMP) and the culprit drug in patients and in 22 negative controls. Immunohistochemical studies were done in the affected skin at the acute phase of the reaction and after a delayed positive skin test/DPT. IFN-γ and IL-4 were quantified in peripheral mononuclear cells, obtained during the positive response to DPT and after resolution of the symptoms. Results From the total number of cases, 12 patients developed urticarial exanthema and 10 maculopapular exanthema after DPT. Only two of the 22 patients (9%) had a positive delayed intradermal skin test: one to AX/AMP and the other to cloxacillin. Biopsies showed a mononuclear CD4, CD8 infiltrate and activated and memory cells. The cytokine expression showed a Th1 pattern in patients, in contrast with the Th0 pattern in controls. Conclusion In patients with non-immediate reactions to BLs (maculopapular exathema or urticarial exanthema), the sensitivity of skin testing is low and DPT may be required to establish the diagnosis. The reproducibility of the reactions and the cytokine pattern expressed during the acute episode support a T cell-induced non-immediate response. [ABSTRACT FROM AUTHOR]

Background Sublingual immunotherapy (SLIT) is a clinically effective treatment in both pollen and house dust mite-induced rhinitis and asthma. However, the mechanisms by which this is accomplished are not clear. Objective The objective of the current study was to establish a mouse model of rhinitis in order to study the effect and mechanisms of SLIT. Methods Mice were sensitized by intraperitoneal injections of alum-adsorbed Phleum pratense extract. Sensitized mice were SLIT-treated and subsequently challenged intranasally and analysed for clinical symptoms, antibody levels, eosinophilia and T cell response. Results Intranasal challenge of sensitized mice led to the development of rhinitis characterized by significantly increased sneezing and influx of eosinophils into the nose. Levels of specific IgE were fivefold increased in nasopharyngeal lavage (NAL) fluid and more than doubled in serum. Furthermore, a T-helper type 2 (Th2) like T cell response was observed in local draining lymph nodes. SLIT treatment of sensitized mice reduced sneezing, eosinophilia and IgE levels in the NAL by more than 50%. Moreover, serum levels of IgE and IgG1 as well as T cell response in the draining lymph nodes were also significantly reduced. Treatment for a shorter time or with a lower dose only led to minor reductions of the clinical and immunological parameters, indicating that the effect of SLIT is time and dose dependent. Conclusion In the present study, we have established a mouse model displaying the hallmarks of allergic rhinitis using a clinically relevant allergen. Using this model, we have demonstrated that SLIT treatment is able to reduce allergic symptoms in a time- and dose-dependent manner. [ABSTRACT FROM AUTHOR]

The T cell branch of the immune system can respond to a virtually infinite variety of exogenous antigens, thus including the possibility of self-antigen recognition and dangerous autoimmune reactions. Therefore, regulatory mechanisms operate both during ontogeny within the thymus and after birth in the periphery. The control of self-reactive T cells occurs through a process of negative selection that results in apoptosis of T cells showing high affinity for self-peptides expressed at the thymic level by means of promiscuous gene expression. Self-reactive T cells escaped to negative selection are controlled in the periphery by other regulatory mechanisms, the most important being natural Foxp3+ T regulatory (Treg) cells. Regulation is also required to control excessive effector T cell responses against exogenous antigens, when they become dangerous for the body. Three types of effector T cells have been recognized: T helper 1 (Th1) cells, which are protective against intracellular bacteria; Th2 cells, which play some role in the protection against nematodes, but are responsible for allergic reactions; Th17 cells, which are probably effective in the protection against extracellular bacteria, but also play a role in the amplification of autoimmune disorders. Abnormal or excessive Th effector responses are regulated by different mechanisms. Redirection or immune deviation of Th1- or Th2-dominated responses is provided by cytokines [interferon-γ (IFN-γ) vs. interleukin-4 (IL-4)] produced by the same cell types and by the CXCR3-binding chemokines CXCL4 and CXCL10. Moreover, both Th1 and Th2 responses can be suppressed by adaptive Treg cells through contact-dependent mechanisms and/or the production of IL-10 and transforming growth factor-β (TGF-β). Finally, TGF-β1 can promote the development of both Th17 effector and adaptive Treg cells, while the contemporaneous production of IL-6 contributes to the development of Th17 cells, but inhibits Treg cells. The development of Th17 cells is also down-regulated by IL-4 produced by Th2 cells and by IFN-γ produced by Th1 cells. [ABSTRACT FROM AUTHOR]

Background Allergen-derived (T cell epitope) peptides may be safer for immunotherapy than native allergen, as they do not cross-link immunoglobulin (Ig)E. However, HLA polymorphism results in multiple potential epitopes. Synthetic peptides of phospholipase (PL) A2 were selected for a peptide vaccine, on the basis of binding affinity for commonly expressed HLA-DR molecules. Objective To evaluate treatment with an HLA-DR-based PLA2 peptide vaccine in subjects with mild honeybee allergy in an open, controlled study. Methods Twelve volunteers with allergy to bee venom received nine intradermal injections of PLA2 peptides, with six untreated subjects serving as controls. Outcome was assessed by the size of the late-phase cutaneous reaction to allergen, peripheral blood mononuclear cell (PBMC) proliferation, cytokine release, and expression of genes associated with immune regulation. Results Subjects receiving peptides showed a decrease in the magnitude of the late-phase cutaneous reaction to bee venom compared with controls ( P=0.03). The proliferation of venom-stimulated PBMCs decreased in treated subjects compared with controls ( P=0.01). Peptide treatment reduced the production of IL-13 by PLA2-stimulated PBMCs ( P<0.01) and IFN-γ ( P<0.01), and increased the production of IL-10 ( P=0.02). Transcription of the suppressor of cytokine signalling ( Socs)3 gene was significantly increased following therapy. A transient, but modest, increase in allergen-specific IgG was also observed. Conclusion HLA-DR-based T cell epitopes modify surrogate markers associated with successful immunotherapy and induction of immune regulation, supporting the concept that this form of treatment may be efficacious in human allergic disease. [ABSTRACT FROM AUTHOR]

Allergen-specific immunotherapy is the only treatment for allergic disease providing long-lasting symptom relief. Currently, it is mainly based on the use of crude allergen extracts. The treatment may be improved by the use of genetically engineered allergens, hypoallergens, aiming at a more effective and safer therapy.The aim of this study was to provide a rational design of hypoallergen candidates for immunotherapy by using structural information and knowledge of B and T cell epitopes of an allergen.The three-dimensional structure of the major cat allergen Fel d 1 was systematically altered by duplication of selected T cell epitopes and disruption of disulphide bonds. Seven Fel d 1 derivatives were generated and screened for allergenic reactivity in comparison with recombinant Fel d 1 in competition-ELISA. The allergenicity was further evaluated in basophil activation experiments and T cell reactivity was assessed in a lymphoproliferation assay.Three out of seven Fel d 1 derivatives, with two duplicated T cell epitopes and one or two disulphide bonds disrupted, were carefully evaluated. The three derivatives displayed a strong reduction in allergenicity with 400–900 times lower IgE-binding capacity than recombinant Fel d 1. In addition, they induced a lower degree of basophil activation and similar or stronger T cell proliferation than recombinant Fel d 1.By a rational approach, we have constructed three Fel d 1 hypoallergens with reduced IgE-binding capacities and retained T cell reactivities. This strategy may be applied to any well-characterized allergen to improve immunotherapy for allergic patients. [ABSTRACT FROM AUTHOR]

The T cell reactivity to the major allergen of bee venom, phospholipase A2, has been thoroughly characterized. In contrast, only little is known about the human cellular response to major allergens from wasp venom.To characterize the human T cell response to antigen 5 fromVespula vulgaris, Ves v 5.Recombinant Ves v 5 was used to establish allergen-specific T cell lines (TCL) and T cell clones (TCC) from the peripheral blood of vespid-allergic and non-allergic individuals. Ves v 5-specific TCL were mapped for T cell epitopes using overlapping synthetic peptides representing the complete amino acid sequence of Ves v 5. Ves v 5-specific TCC were analysed for antigen-induced secretion of IL-4, IFN-γ and IL-10.Seventeen distinct T cell epitopes were recognized by allergic individuals among which Ves v 5181–192 was identified as a dominant T cell epitope. Partially different epitopes were observed in TCL from non-allergic subjects and the dominant epitope Ves v 5181–192 was not prevalent in these cultures. Ves v 5-specific TCC isolated from allergic individuals did not show the typical T helper type 2 (Th2)-like cytokine profile in response to specific stimulation, i.e. high amounts of IL-4 and low IFN-γ. TCC from non-allergic individuals showed a Th1-like cytokine pattern.Our findings provide evidence that the allergic T cell response to Ves v 5 is not Th2-dominated and that different immunogenic sites on this major wasp venom allergen are recognized by allergic and non-allergic individuals. [ABSTRACT FROM AUTHOR]

In spite of significant safety measures, allergy to industrial enzymes remains a major concern. The increasing prevalence of occupational allergy emphasizes the need to investigate the functional properties of enzyme-exposed dendritic cells (DCs), as DCs possess a potent ability to activate allergen-specific T cells.This study aims at elucidating the molecular mechanisms underlying allergic immune responses to lipase, an industrial enzyme. For this purpose, we studied the effect of both hypoallergenic and wild-type lipase on the transcriptional regulation in DCs and their stimulatory effect on memory CD4+ T cells.Five individuals with documented lipase allergy were tested for specific serum IgE. DCs from these individuals, stimulated with lipases, were assayed for their ability to affect proliferation and polarization of memory T cells. The effect of lipases on transcriptional activity in DCs was evaluated using global expression analysis.Lipase-specific IgE levels varied considerably between donors, with donor 4 exhibiting highest levels, and a potent specific CD4+ T cell recall response was demonstrated only for donor 4. No difference was detected in cytokine profile when T cells from donor 4 were co-cultured with DCs pulsed with either hypoallergenic or wild-type lipase, as demonstrated by high IL-4 and IL-13, and low IFN-γ production. However, the lipases induced different genetic signatures in DCs from donor 4, as compared with the non-responders.DCs from individuals with clinically diagnosed allergy to lipase displayed a differential response to stimulation with hypoallergenic and wild-type lipasein vitro. Only allergen-pulsed DCs from donor 4 were able to induce CD4+ T cell proliferation. The lipase-specific T cells displayed a T-helper type 2 phenotype, which was not altered by hypoallergenic lipase-pulsed DCs. Furthermore, DCs derived from donor 4 and stimulated with either of the lipases displayed different transcriptional profiles, as compared with the other donors. These signatures represent genes of potential importance for an immunoregulatory role of DC in an ongoing allergic response. [ABSTRACT FROM AUTHOR]

Laboratory animal allergy (LAA) is an important cause of occupational sensitization and asthma. Rats are a frequent cause of LAA and the major rat allergen, Rat n 1, is a member of the lipocalin protein family, which includes several other animal allergens such as the cow allergen, Bos d 2. To date, Bos d 2 is the only mammalian lipocalin allergen to have been studied in detail.We undertook a cross-sectional study of a large population of individuals exposed to laboratory rats to determine the proliferative responses of peripheral blood mononuclear cells (PBMCs) to the major rat allergen, Rat n 1.Eighty-three cases (defined by a positive skin prick test (SPT)⩾3 mm and/or a positive RAST⩾2% binding) and 274 referents without specific IgE to rats were tested for their proliferative responses of PBMCs to rat allergen. Cytokine release to rat urinary protein was examined in 28 sensitized and 42 non-sensitized exposed individuals.Proliferation to rat urinary protein was weak in all individuals. Four regions within Rat n 1 were identified as containing potential immunodominant T cell epitopes and three of these co-localized within the conserved regions of the lipocalin molecule. All four regions within Rat n 1 overlapped considerably with the characterized epitopes of the lipocalin allergen, Bos d 2. IL-5 and ratios of IL-5/IFN-γ were significantly increased in cases.The response to Rat n 1 is remarkably similar to the cow lipocalin allergen Bos d 2. T cell epitopes within lipocalins appear to co-localize with the conserved regions of the molecule. LAA is characterized by an increased production of IL-5. Investigation of other lipocalin allergens will provide further information about the allergenicity of this group of proteins. [ABSTRACT FROM AUTHOR]

Clinically effective subcutaneous allergen-specific immunotherapy (SIT) is associated with altered circulating T cell cytokine production and altered local cytokine responses with increased IL-10 following allergen challenge in target organs. This study aimed to elucidate mechanisms for these T cell changes, by examining surface expression of markers for peripheral tissue trafficking on circulating cytokine-positive T cells following standardized house dust mite- (HDM-) SIT. A randomized conventional HDM immunotherapy study was performed on a panel of 12 HDM-allergic subjects. Nine subjects received treatment with conventional HDM immunotherapy using a standardized extract and three subjects were treated by standard pharmacotherapy alone. Symptom and medication scores and allergen-induced cutaneous late-phase responses were assessed before and 9 months after institution of therapy. Before and at 3 and 9 months of SIT, peripheral blood mononuclear cells were cultured for 14 days with HDM extract and CD4+ and CD8+ T cell expression of CD62L, CD49d and CCR5 and production of IL-10, IFN-γ and IL-4 were analysed by flow cytometry. Allergen-specific T cell proliferation was assessed by 3H-thymidine incorporation. At 9 months, all SIT-treated patients showed reduced symptom scores and late-phase cutaneous responses to HDM compared with baseline levels. The proportions of CD4+ T cells which were IL-10+ were increased ( P<0.01), and the proportions of CD4+ and CD8+ T cells which were IL-4+ decreased ( P<0.05) compared with baseline. CD4+ and CD8+ T cell IFN-γ production, expression of surface markers for peripheral tissue trafficking and allergen-specific proliferation remained unchanged during SIT treatment. However, increased proportions of CD4+CD62L−, CD4+CD49dhi, CD4+CCR5+ T cells expressing IL-10 were detected at 9 months of SIT compared with baseline ( P<0.05). IL-10 staining co-localized with CD4+CD25+ T cells. Clinically effective subcutaneous immunotherapy with a standardized HDM Dermatophagoides pteronyssinus preparation results in decreased numbers of IL-4+ T cells and expansion of CD4+IL-10+ T cells expressing a peripheral tissue trafficking phenotype. The co-localization of IL-10+ staining to CD4+CD25+ T cells is consistent with the induction of a T regulatory cell population by SIT. [ABSTRACT FROM AUTHOR]

Respiratory viral infections are a leading cause of the hospitalization of asthmatics, however, the cellular immunological interactions which underlie these two diseases remain elusive. We sought to characterize the effect influenza viral infection has on allergic airway inflammation and to identify the cellular pathways involved. We have used an ovalbumin (OVA) model of allergic airway inflammation, which involves sensitization of animals with OVA adsorbed in alum adjuvant followed by an intranasal challenge with OVA in phosphate-buffered saline. To study T cell recruitment into the lung, we adoptively transferred in vitro activated T cell receptor-transgenic T cells, which were subsequently identified by fluorescence-activated cell sorting (FACS) analysis. In addition, to study in vivo dendritic cell (DC) migration, we administered fluorescently labelled dextran and identified DCs that had phagocytosed it by FACS analysis. We found that different stages of influenza infection had contrasting effects upon the outcome of OVA-induced allergic airway inflammation. The allergic response against OVA was exacerbated during the acute stage of influenza infection; however, mice were protected against the development of airway eosinophilia at late time-points following infection. We investigated the mechanisms responsible for the virus-induced exacerbation and found that the response was partially independent of IL-4 and that there was increased delivery of inhaled allergens to the draining lymph node during the acute stage of the infection. In addition, virus-induced inflammation in the lung and draining lymph node resulted in the non-specific recruitment of circulating allergen-specific effector/memory cells. In addition to virus-mediated damage to the lung and airways, influenza viral infection can also enhance unrelated local allergic responses. [ABSTRACT FROM AUTHOR]

Allergen-induced sensitization and airway disease are the results of adverse immune reactions against environmental antigens that may be prevented or inhibited by immune modifying strategies. To investigate the effects of the novel immune response modifier resiquimod (R-848), from the family of imidazol-derivates, in a murine model of allergen-mediated Th2-immune responses and concomitant airway inflammation and airway hyper-reactivity. BALB/c mice were systemically sensitized with ovalbumin (OVA) on days 1 and 14 and challenged with OVA aerosol on days 28 and 29. R-848 was applied intranasally to sensitized animals once prior to the first allergen airway challenge, on day 27. A single application of R-848 significantly reduced numbers of eosinophils and lymphocytes in bronchoalveolar lavage fluid and inhibited mucus gland hyperplasia, compared with sensitized and challenged controls. Associated with the decrease in airway inflammation, single intranasal treatment with R-848 abolished the development of airway hyper-reactivity after allergen sensitization and airway challenges. Additionally, Th2-cytokine production in lung tissues from sensitized and R-848-treated animals was reduced, whereas IL-12 and IFN-γ production was increased, compared with non-treated sensitized mice. These data indicate that R-848 effectively inhibits allergen-induced airway inflammation and hyper-reactivity by modulation of increased Th2-immune responses. [ABSTRACT FROM AUTHOR]

Allergens are common non-infectious antigens to which people will mount T cell dependent humoral responses. Among genetically susceptible individuals, an antigen-specific response results involving the production of allergen-specific IgE (atopy). Determine if this susceptibility is manifested as an inherited, allergen-specific trait or a random response to allergens among susceptible people. We evaluated allergen-specific outcomes in 1099 members of families with positive atopic history (26 multi-generation and 112 nuclear families). Each was tested for sensitivity to 14 common allergens by standardized skin prick test (SPT), a marker of specific IgE production. Over 15 000 individual SPT's were evaluated. Among five randomly selected multi-generation families ( N=163), semi-quantitative determinations of Amb a 1-specific IgA1,2 and IgG1–4 were determined in three groups: (A) Amb a SPT+/Amb a 1-IgE+, (B) Amb a SPT−/Amb a 1-IgE+, (C) Amb a SPT−/Amb a 1-IgE−. By rank correlation statistics, there were no discernible ‘patterns’ of specific SPT outcomes among any of the multi-generation families, suggesting that environmental exposure rather than allergen-specific inheritance determined the responses. This was confirmed among the nuclear families since the conditional SPT outcomes among children were independent of the SPT responses of their parents. Among five randomly selected multi-generation families, the relative proportionate concentrations of the Amb a 1-specific IgA and IgG subclasses were comparable, regardless of atopic sensitization to the ragweed allergen Amb a. While the general propensity for atopy may be inherited, an individual's specific atopic outcome is a random variable independent of familial sensitization patterns. [ABSTRACT FROM AUTHOR]