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We study a mathematical model of immune response by T cells where the regulatory T cells (Treg) inhibit interleukin 2 (IL‐2) secretion. We model the suppression of the autoimmune line of T cells after a different line of T cells responded to a pathogen infection. In this paper, we show that if the population of the pathogen responding line of T cells becomes large enough, the competition for IL‐2 and the increase in the death rates may lead to a depletion in the concentration of autoimmune T cells. Provided this lasts for a sufficiently long time, the concentration of autoimmune T cells can be brought down to values inside the basin of attraction of the controlled state, and autoimmunity can be suppressed. [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]

While there is a vast array of aetiologies that may lead to chronic pruritus, recent data suggests that many of these conditions share similar interactions between keratinocytes, nerves, and the immune system. Specifically, the type 2 immune response, including Th2 T Cells and their related cytokines, has been noted to play a major role in the development of pruritus in a variety of itchy conditions. To date, atopic dermatitis is the most striking example of this pathogenesis. However, the body of literature supporting its role in many other itchy conditions, including other inflammatory, bullous, as well as systemic diseases, continues to grow. In addition, new treatments targeting this type 2 immune system continue to be developed and investigated. In the current review, we present the current body of literature supporting the role of the type 2 immune response in itchy conditions beyond atopic dermatitis as well as potential therapeutic options that target this pathway for chronic itch. [ABSTRACT FROM AUTHOR]

Aims: Leishmaniasis is considered a disease with multiple clinical/immunopathological characteristics, depending on the immunity of the host and the species of the parasite. In Panama, the most prevalent species that causes localized cutaneous leishmaniasis (LCL) is Leishmania (Viannia) panamensis, and its immune response is poorly studied. Therefore, we evaluated by immunohistochemistry, the in situ immune response during this infection. Methods and Results: Biopsies from Panamanian patients with LCL were collected and processed by histological techniques. Infection by L. (V.) panamensis was demonstrated by isolation in culture and molecular characterization by Hsp70‐RFLP. The in situ immune response was assessed by immunohistochemistry. The immune response was characterized by predominance of T cells, mainly CD8 cells that showed positive correlation with IFN‐γ and Granzyme B. CD4 cells presented positive correlation with both IFN‐γ and IL‐13, pointed by mixed cellular immune response. Regulatory response was characterized by FoxP3 cells, which showed positive correlation to IL‐10 but not with TGF‐β. Conclusions: L. (V.) panamensis infection triggers a mixed cellular immune response, characterized by the presence of pro‐inflammatory, anti‐inflammatory and regulatory elements in the skin lesion of Panamanian patients. These data contribute to a better understanding of the immunopathogenesis of Leishmania Viannia infection in Panama. [ABSTRACT FROM AUTHOR]

Background and Purpose: Inflammatory bowel disease (IBD) is a chronic and relapsing inflammatory disorder of the gastrointestinal tract, and an impaired immune response plays a critical role in IBD. The current drugs and therapies for IBD treatment are of limited use, therefore, there is a need to find novel drugs or therapies for this disease. We investigated the effect of cambogin in a mouse model of dextran sulphate sodium (DSS)-induced colitis and whether cambogin attenuates inflammation via a Treg-cell-mediated effect on the immune response.Experimental Approach: Chronic colitis was established in mice using 2% DSS, and cambogin (10 mg·kg-1 , p.o.) was administered for 10 days. Body weight, colon length and colon histology were assessed. Cytokine production was measured using elisa and quantitative real-time PCR. To evaluate the mechanism of cambogin, human CD4+ CD25hi CD127lo Treg cells were isolated from peripheral blood mononuclear cells. Major signalling profiles involved in Treg cell stability were measured.Key Results: Cambogin attenuated diarrhoea, colon shortening and colon histological injury and IL-6, IFN-γ and TNF-α production in DSS-treated mice. Cambogin also up-regulated Treg cell numbers in both the spleen and mesenteric lymph nodes. Furthermore, cambogin (10 μM) prevented Foxp3 loss in human primary Treg cells in vitro, and promoted USP7-mediated Foxp3 deubiquitination and increased Foxp3 protein expression in LPS-treated cells.Conclusions and Implications: The effect of cambogin on DSS-induced colitis is expedited by a Treg-cell-mediated modification of the immune response, suggesting that cambogin could be applied as a novel agent for treating colitis and other Treg cell-related diseases. [ABSTRACT FROM AUTHOR]

There is a current lack of effective mucosal vaccines against major gastroenteric pathogens and particularly against Helicobacter pylori, which causes a chronic infection that can lead to peptic ulcers and gastric cancer in a subpopulation of infected individuals. Mucosal CD4+ T-cell responses have been shown to be essential for vaccine-induced protection against H. pylori infection. The current study addresses the influence of the adjuvant and site of mucosal immunization on early CD4+ T-cell priming to H. pylori antigens. The vaccine formulation consisted of H. pylori lysate antigens and mucosal adjuvants, cholera toxin ( CT) or a detoxified double-mutant heat-labile enterotoxin from Escherichia coli (dm LT), which were administered by either the sublingual or intragastric route. We report that in vitro, adjuvants CT and dm LT induce up-regulation of pro-inflammatory gene expression in purified dendritic cells and enhance the H. pylori-specific CD4+ T-cell response including interleukin-17A ( IL-17A), interferon- γ ( IFN- γ) and tumour necrosis factor- α ( TNF- α) secretion. In vivo, sublingual immunization led to an increased frequency of IL-17A+, IFN- γ+ and TNF- α+ secreting CD4+ T cells in the cervical lymph nodes compared with in the mesenteric lymph nodes after intragastric immunization. Subsequently, IL-17A+ cells were visualized in the stomach of sublingually immunized and challenged mice. In summary, our results suggest that addition of an adjuvant to the vaccine clearly activated dendritic cells, which in turn, enhanced CD4+ T-cell cytokines IL-17A, IFN- γ and TNF- α responses, particularly in the cervical lymph nodes after sublingual vaccination. [ABSTRACT FROM AUTHOR]

It is becoming increasingly clear that the T-cell-mediated immune response is important in many diseases. In this study, we used concanavalin A (Con A) -induced hepatitis to investigate the role of CD49a in the molecular and cellular mechanism of the T-cell-mediated immune response. We found that CD49a-/- mice had significantly reduced levels of serum alanine aminotransferase and were protected from Con Ainduced hepatitis. CD49a deficiency led to decreased production of interferon-γ (IFN-γ) and interleukin-17A (IL-17A) after Con A injection. Furthermore, we found that hepatic CD4+ T cells and invariant natural killer T cells up-regulated CD49a expression, along with enhanced activation after Con A injection, leading to production of inflammatory cytokines by these T cells. Blockade of CD49a in vivo ameliorated Con A-induced hepatitis with reduced production of IFN-γ and IL-17A. Hence, CD49a promoted Con A-induced hepatitis through enhancing inflammatory cytokine production (IFN-γ and IL-17A) by CD4+ T and invariant natural killer T cells. The protective effect of CD49a blockade antibody suggested a new target therapeutic molecule for intervention of T-cell-mediated liver injury. [ABSTRACT FROM AUTHOR]

Background and Aim T-cell responses against hepatitis C are believed to be critical in achieving both natural and treatment-induced clearance. However, rapid clearance of antigen with early treatment of primary infection may result in reduced or poorly sustained cellular immunity. This study longitudinally examined Th1 and Th2 hepatitis C virus ( HCV)-specific cytokine production and T-cell effector function from subjects enrolled in the Australian Trial in Acute Hepatitis C comparing three groups: treatment-induced clearance (sustained virological response [ SVR]), treatment non-response, and untreated spontaneous clearance. Methods HCV-specific T-cell responses were characterized by HCV peptide ELISpot, in vitro cytokine production, and T-cell flow cytometry assays. Results Treated subjects with a sustained virological response ( SVR) displayed a better maintenance of HCV-specific Th1 responses compared to treatment non-responders (higher interferon [ IFN]-γ and interleukin ( IL)-2 magnitude at week 24, broader IFN-γ responses at weeks 24 and 48, P < 0.05) and significantly increased IFN-γ responses between screening and week 48 (magnitude P = 0.026, breadth P = 0.009). Treatment-induced viral clearance was also associated with a trend toward decreased IL-10 responses (screening to week 48, P = 0.070), higher expression of CD45 RO ( P = 0.042) and CD38 ( P = 0.088) on CD4+ T cells, and higher IFN-γ R expression ( CD56+ IFN-γ R+ P = 0.033) compared to treatment non-responders. Untreated subjects with viral clearance also displayed high magnitude and broad HCV-specific IFN-γ and IL-2 responses early in infection; however, IFN-γ responses were not as well maintained compared to treated subjects with a SVR (week 48 magnitude, breadth P = 0.064). Conclusion Treatment-induced viral clearance of recent HCV infection is associated with maintenance of HCV-specific Th1 responses. [ABSTRACT FROM AUTHOR]

Signal transducer and activator of transcription 1 (Stat1) mediates anti-viral responses and cytokine-driven anti-proliferative, apoptotic and immunomodulatory activities. As de-regulated Stat1 function can affect tumour progression we sought to elucidate the effects of tumour cell-intrinsic Stat1 expression on immunosurveillance. Knockout of Stat1 enhanced the development of sarcomas induced by the chemical carcinogen 3-methylcholanthrene (MCA). Growth of transplanted MCA-induced Stat1−/− sarcomas was suppressed in wild-type mice compared to growth in Stat1−/− and immunocompromised recipients. Co-depletion of NK and CD8+ T cells from wild-type mice facilitated Stat1-deficient tumour growth whereas depletion of CD4+ T cells and CD8+ T cells did not. In vitro and in vivo analysis of the tumours implicated a role for NK cell-mediated, perforin-dependent killing of Stat1-deficient tumours. Interestingly, restoration of Stat1 expression in Stat1−/− tumours resulted in diminished involvement of NK cells and increased contribution of CD8+ T cells in anti-tumour responses. Therefore, Stat1 expression within tumour cells modulated anti-tumour immune responses by altering the dominant immune effector cell involvement from NK cells to CD8+ T cells in the absence or presence of Stat1 respectively. [ABSTRACT FROM AUTHOR]

Summary T cells simultaneously producing multiple cytokines and possessing cytotoxic capacity termed polyfunctional cells (PFCs) are increasingly recognized as the immune correlate of protection against pathogenic viruses. We investigated co-expression of four cytokines (interferon-γ, macrophage inflammatory protein 1-α, tumour necrosis factor-α and interleukin-2) and degranulation capacity (CD107a surface expression) of Epstein-Barr virus (EBV) -specific CD4+ and CD8+ T cells upon stimulation by overlapping peptides of EBV lytic (BZLF1) and latent (EBNA1, EBNA3 and LMP2) proteins, in 20 healthy Chinese long-term carriers. Two patients with post-transplant lymphoproliferative disorder (PTLD), who had impaired T-cell immunity, were studied for comparison. Both EBV-specific CD4+ and CD8+ PFCs were readily generated in long-term carriers and showed immunodominance hierarchies of latent proteins (EBNA1 > EBNA3/LMP2 and EBNA3 > LMP2 > EBNA1 for CD4+ and CD8+ T cells, respectively), as evidenced by a higher proportion of PFCs generated by immunodominant EBV proteins than by subdominant viral proteins. In contrast, the proportion of EBV-specific PFCs was markedly decreased in patients with PTLD. The EBV-specific PFCs produced more cytokine per cell than single-functional T cells and comprised different subsets. Five-functional CD4+ and CD8+ T cells were detected and four-functional CD4+ T cells were mainly CD107a negative and expressed all four cytokines whereas four-functional CD8+ T cells were mainly CD107a positive and expressed three of the four cytokines (interleukin-2-negative). We conclude that EBV-specific PFCs are generated in much higher proportions in the long-term carriers than in the patients with PTLD and maintain the immunodominant characteristics of the virus. [ABSTRACT FROM AUTHOR]

Summary Many parasitic helminth infections induce Th2-type immune responses and engage the regulatory network. In this study, we specifically investigated the influence of antigens derived from different life stages of the helminth Trichinella spiralis on the polarization of naive CD4+ T cells by dendritic cells. Results obtained from C57BL/6 mice showed that T. spiralis derived antigens have the capacity to induce bone marrow-derived dendritic cells to acquire an incompletely mature phenotype that promotes a significant proliferation of naive CD4+ T cells and a mixed Th1/Th2 cytokine profile with the predominance of Th2 cytokines. Increased production of IL-4, IL-9, IL-10 and IL-13 accompanied increased IFN-γ. Furthermore, dendritic cells pulsed with T. spiralis antigens did not induce an increase in the population of Foxp3+ T regulatory cells. Although other helminth antigens have demonstrated the capacity to induce de novo generation of Foxp3+ T regulatory cells, here our in vitro studies provide no evidence that T. spiralis antigens have this capacity. [ABSTRACT FROM AUTHOR]

Type 2 T helper (TH2) cells are critical for the development of allergic immune responses; however, the molecular mechanism controlling their effector function is still largely unclear. Here, we report that the transcription factor NFIL3/E4BP4 regulates cytokine production and effector function by TH2 cells. NFIL3 is highly expressed in TH2 cells but much less in TH1 cells. Production of interleukin (IL)-13 and IL-5 is significantly increased in Nfil3−/− TH2 cells and is decreased by expression of NFIL3 in wild-type TH2 cells. NFIL3 directly binds to and negatively regulates the Il13 gene. In contrast, IL-4 production is decreased in Nfil3−/− TH2 cells. Increased IL-13 and IL-5 together with decreased IL-4 production by antigen-stimulated splenocytes from the immunized Nfil3−/− mice was also observed. The ability of NFIL3 to alter TH2 cytokine production is a T-cell intrinsic effect. Taken together, these data indicate that NFIL3 is a key regulator of TH2 responses. [ABSTRACT FROM AUTHOR]

Plasmid DNA vaccination using skin electroporation (EP) is a promising method able to elicit robust humoral and CD8+ T-cell immune responses while limiting invasiveness of delivery. However, there is still only limited data available on the induction of CD4+ T-cell immunity using this method. Here, we compare the ability of homologous prime/boost DNA vaccinations by skin EP and intramuscular (i.m.) injection to elicit immune responses by cytokine enzyme-linked immunosorbent spot (ELISPOT) assay, as well as study the complexity of CD4+ T-cell responses to the human immunodeficiency virus antigen Gag, using multiparamater flow cytometry. We find that DNA vaccinations by skin EP and i.m. injection are capable of eliciting both single- and poly-functional vaccine-specific CD4+ T cells. However, although DNA delivered by skin EP was administered at a five-fold lower dose it elicited significant increases in the magnitude of multiple-cytokine producers compared with i.m. immunization suggesting that the skin EP could provide greater poly-functional T-cell help, a feature associated with successful immune defense against infectious agents. [ABSTRACT FROM AUTHOR]

The efficacy of vaccines can be greatly improved by adjuvants that enhance and modify the magnitude and the duration of the immune response. Several approaches to design rational adjuvants are based on the suppression of regulatory T-cell (Treg) function. Here, we evaluated whether removal or addition of Treg at the time of vaccination with tetanus toxoid and the mucosal adjuvant cholera toxin (CT), would affect immune responses. We found that depletion/inactivation of CD4+CD25+ Treg, either by treatment of BALB/c mice with anti-CD25 monoclonal antibodies or by adoptive transfer of CD4+CD25− T lymphocytes depleted of CD4+CD25+ Treg into nu/nu mice, impaired antibody production after mucosal immunization in the presence of CT. Conversely, transfer of polyclonal, but not Ag-specific, CD4+CD25+Foxp3+ Treg to normal BALB/c mice enhanced CT-induced antibody responses. An increased titer of both immunoglobulin IgG1 and IgG2a antibody subclasses was found, however, the ratio between IgG1/IgG2a with or without polyclonal Treg was comparable, suggesting that polyclonal Treg influence the magnitude, but not the quality of the immune response. Recipients of polyclonal Treg that had been immunized with CT had an increased number of Ag-specific CD4+ T cells with an activated phenotype (CD44hi) in the draining lymph nodes. This accumulation of Ag-specific CD4+ T lymphocytes could favour the germinal centre formation and may promote T-dependent B-cell responses. Overall, our study indicates that Foxp3+ Treg can not only function as suppressor cells but also as helper T cells, depending on the type of immune response being evaluated and the microenvironment in which the response is generated. [ABSTRACT FROM AUTHOR]

Mouse infection with intracellular bacteria induces a potent inflammatory response that requires protective mechanisms to avoid infection-induced immune pathology. CD69 is expressed in all leukocytes during activation after infection with a wide range of microbial pathogens. This study explores the way in which CD69 affects cell activation after Listeria monocytogenes (Lm) infection and its effects on host protection. We show that infectivity and bacterial clearance capability are unaltered in CD69−/− peritoneal macrophages, bone marrow-derived macrophages and dendritic cells. We found no major altered cell populations in splenocytes of Lm-infected CD69−/− mice. However, an increase in the expression of Th1 cytokines was observed after infection, with increased production of type I and II interferon (IFN). In addition, CD69−/− splenocytes showed increased apoptosis, consistent with IFN enhancement of lymphocyte apoptosis in response to Lm infection. CD69−/− mice showed liver and spleen damage, and greatly increased susceptibility to Lm infection, compared with wild-type controls. Lm-specific T cells were decreased in CD69−/− mice even if T-cell cross-presentation and T-cell intrinsic priming response were not compromised. As listeriosis was increased as early as day 1 post-infection but CD69−/−RAG2−/− mice were more efficient at controlling Listeria, we propose that CD69 controls the cross-talk between innate components and lymphocytes. These results highlight a role for CD69 in preventing infection-induced immunopathology. [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 Cellula r immune responses play a critical role in providing help for the production of neutralizing antibodies to influenza virus, as well as producing anti-viral cytokines and killing infected cells in the lung. Heterosubtypic T-cell responses between different subtypes of influenza have been shown to exist in humans and to provide protection against morbidity and mortality associated with H5N1 infection in animal challenge models. Therefore, existing T-cell responses induced by natural infection or vaccination in humans may provide some degree of protection from infection with H5N1 strains, or may attenuate the severity of disease. Objectives To investigate heterosubtypic T-cell responses to avian influenza in humans. Methods T-cell responses to an overlapping set of H5 HA peptides and inactivated viruses (H1N1, H3N2 and H5N1) were assessed using IFN-γ and IL-2 enzyme-linked immunospot (ELISpot) assays in a cohort of adults either vaccinated against seasonal influenza in the last 3 years ( n = 20) or previously infected ( n = 40). Results T-cell responses to all three subtypes of virus were found in both infected and vaccinated individuals by IFN-γ and IL-2 ELISpot assays. Approximately half of the participants from each group had a positive T-cell response to the H5 HA peptides in the IFN-γ or IL-2 ELISpot assay. Conclusions Heterosubtypic T-cell responses to H5 HA occur quite frequently in vaccinated and infected individuals. Further investigation of these responses and what role they may play upon challenge or vaccination against H5N1 may assist in vaccine design for avian influenza. [ABSTRACT FROM AUTHOR]

Tight control of T-cell proliferation and effector function is essential to ensure an effective but appropriate immune response. Here, we reveal that this is controlled by the metalloprotease-mediated cleavage of LAG-3, a negative regulatory protein expressed by all activated T cells. We show that LAG-3 cleavage is mediated by two transmembrane metalloproteases, ADAM10 and ADAM17, with the activity of both modulated by two distinct T-cell receptor (TCR) signaling-dependent mechanisms. ADAM10 mediates constitutive LAG-3 cleavage but increases ∼12-fold following T-cell activation, whereas LAG-3 shedding by ADAM17 is induced by TCR signaling in a PKCθ-dependent manner. LAG-3 must be cleaved from the cell surface to allow for normal T-cell activation as noncleavable LAG-3 mutants prevented proliferation and cytokine production. Lastly, ADAM10 knockdown reduced wild-type but not LAG-3−/− T-cell proliferation. These data demonstrate that LAG-3 must be cleaved to allow efficient T-cell proliferation and cytokine production and establish a novel paradigm in which T-cell expansion and function are regulated by metalloprotease cleavage with LAG-3 as its sole molecular target. [ABSTRACT FROM AUTHOR]

We have previously shown that the major dog allergen Can f 1 contains seven T cell epitope regions, none of which was preferentially recognized. To identify the immune characteristics of Can f 1 epitopes and to verify their suitability for peptide-based allergen immunotherapy, short-term T cell lines were generated with epitope-containing peptides from peripheral blood mononuclear cells of Can f 1 skinprick test-positive allergic and healthy control subjects. The lines were examined for their proliferative capacity and cytokine production upon stimulation with the allergen peptide, a homologous peptide from human tear lipocalin (TL) and Can f 1 and TL proteins. Can f 1 peptides induced proliferation of T cells and gave rise to T cell lines with comparable efficiencies. In particular, the T cell lines of allergic subjects induced with p33–48 and p107–122 favoured the production of interferon-γ and interleukin-10, respectively. A greater number of Can f 1-specific T cell lines were generated from allergic than from healthy individuals. Two p107–122-induced Can f 1-specific T cell lines also reacted to a homologous peptide of human TL. Our results suggest that several T cell epitope-containing peptides should be used in combination for specific immunotherapy in Can f 1 allergy. [ABSTRACT FROM AUTHOR]

Moed H, von Blomberg M, Bruynzeel DP, Scheper R, Gibbs S, Rustemeyer T. Improved detection of allergen-specific T-cell responses in allergic contact dermatitis through the addition of ‘cytokine cocktails’. The gold standard for the diagnosis of allergic hypersensitivity is skin patch testing with the suspected allergens. This diagnostic tool, however, has distinct disadvantages, and therefore the development of alternative or complementary in vitro tests is of great importance. In this study, we evaluate the applicability of an in vitro test method, as developed earlier for nickel allergy, to detect allergen-specific T cells in the blood of patients allergic to frequent sensitizers (chromate, cobalt, paraphenylenediamine, fragrances and chloromethyl-isothiazolinone). Peripheral blood mononuclear cells (PBMCs) of allergic patients and healthy controls were cultured in the absence or presence of allergen. Additionally, type 1 (IL-7 and IL-12) or type 2 (IL-7 and IL-4) stimulating cytokines were added; after 6-day proliferation, IFN-γ and IL-5 secretions were determined. Without the addition of cytokines, consistent allergen-induced proliferation was observed in PBMCs of nickel-allergic patients only. By contrast, the addition of type 1 or type 2 stimulating cytokines resulted in a significantly enhanced allergen-specific proliferation for all allergens tested (sensitivity increased from 26 to 43% or 38%, respectively, P < 0.05). In these cultures, allergen-induced IFN-γ and IL-5 secretion was also significantly increased, compared to healthy controls ( P < 0.05, for IFN-γ sensitivity 79%, specificity 93%; for IL-5 sensitivity 74%, specificity 81%). In conclusion, these results demonstrate an increased proliferative capacity and cytokine production by allergen-specific T cells from allergic patients, but not of healthy individuals upon stimulation with allergens in combination with type 1 or 2 skewing cytokines. The present data warrant further exploration of the application of this test to a broader set of allergens. [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]

A CD8+ T cell of naive phenotype has multiple career choices during its primary differentiation into an effector cell population. One of these career options is becoming a CD8low T cell. We have previously shown by in vitro studies that CD8low T cells have lost expression of CD8 surface protein and mRNA and are poorly cytolytic. In line with poor cytolytic function, CD8low T cells express low levels of perforin and granzyme B and C, mediators of the granule-exocytosis machinery. However, CD8low T cells express IFN-γ and substantial amounts of IL-4, the signature cytokines of type 1 and type 2 T-cell polarization, respectively. Here, we argue that the CD8low phenotype is an alternative career choice for any naive CD8+ T cell during primary activation but that the probability of choosing this option is greatly enhanced by both IL-4 and strong activation conditions. CD8low T cells have downregulated CD8α/β heterodimers and no preferential CD8α/α homodimer expression. As shown by anti-CD8 Ab blocking experiments, surface CD8 substantially contributes to the CD8 T cell's effector function (i.e. cytokine expression and cytolytic activity). The distinct effector profile of CD8low T cells gives an example of the complexity of different CD8 T cell careers during primary effector differentiation. [ABSTRACT FROM AUTHOR]

To investigate the role of T lymphocytes in the immune response to Echinococcus granulosus , using sheep hydatid fluid (SHF) and antigen B (AgB), we generated T-cell lines from patients with active, transitional and inactive hydatid cysts. We established 16 T-cell lines, eight specific to SHF and eight specific to AgB. At surface phenotyping 88–98% of cells displayed the helper/inducer CD4 antigen. In all patients, at all clinical stages of hydatid cyst disease, T-cell stimulation with SHF and AgB invariably amplified a large number of almost identical Vβ subfamily fragments. Irrespective of antigen-specificity, the two cell lines from the patient with an inactive cyst had a Th1 profile, because they exclusively expressed and produced IFN-γ. Conversely, the T-cell lines derived from the seven patients with active and transitional hydatid cysts had mixed Th1/Th2 and Th0 clones. The functional characteristics of the 16 T-cell lines differed markedly in the various clinical stages of cystic echinococcosis, thus providing new in vitro evidence that Th1 lymphocytes contribute decisively to the inactive stage of hydatid disease, Th2 lymphocytes in the active and transitional stages. The parasite-specific T-cell lines, especially the two Th1 lines from the patient with an inactive cyst, may help identify Th1 protective epitopes on SHF and AgB. [ABSTRACT FROM AUTHOR]

In this study interleukin (IL)-15 was examined for its ability to modulate the expression of interferon-γ (IFN-γ) and IL-4 in activated human T lymphocytes. The effect of IL-15 was compared with IL-2 and IL-7, cytokines all known to use the IL-2 receptor γC chain. The results demonstrate that the extent of upregulation of IFN-γ and IL-4 mRNA was dependent on the applied cytokine (IL-2>IL-15>IL-7) and on the stimulatory signal. IFN-γ and IL-4 mRNAs were upregulated by IL-15 in concanavalin A- (twofold) and anti-CD3 plus anti-CD28- (fivefold) stimulated T lymphocytes. IFN-γ mRNA accumulation, but not IL-4 mRNA, was additively upregulated by IL-15 plus IL-7 (ninefold) in anti-CD3 stimulated T lymphocytes, and bypassed the requirement of CD28 signalling. Fluorescence-activated cell sorting (FACS) experiments demonstrated that IFN-γ mRNA was upregulated by IL-15 in both CD4+ and CD8+ T lymphocytes, whereas IL-4 mRNA accumulation predominantly occurred in CD4+ cells. Preincubation of highly purified CD4+ T lymphocytes during 7 days with IL-15 and/or IL-7, followed by activation, also showed enhanced IL-4 protein secretion, but predominantly upregulated IFN-γ protein. The net effect was a dramatically increased IFN-γ/IL-4 ratio. Taken together, IL-15 and IL-7 can act as costimulatory signals, which may favour a T helper 1 (Th1) immune response, particularly in the absence of sufficient CD28 costimulation. [ABSTRACT FROM AUTHOR]

There is substantial evidence from experiments of nature that immune competence plays a major part in determining the outcome of anogenital human papillomavirus (HPV) infection. Cellular rather than humoral immunity would appear to be the key to the control and eradication of HPV-induced warts. It seems likely that the HPV early proteins, which are responsible for viral replication (E1 and E2) and for promoting tissue proliferation (E6 and E7) will be the target antigens recognized by antigen-specific T cells. Natural infection is slow to produce an appropriate therapeutic immune response to these proteins, probably because HPV has adopted a strategy to prevent the effective presentation of viral antigens to the host immune system. Human papilomavirus infection is non-lytic so there is little release of viral antigen to professional antigen-presenting cells. Additionally no local pro-inflammatory cytokine production and no local inflammation is induced by HPV infection. An optimal therapeutic strategy for anogenital HPV infection would be, therefore, to accelerate the induction of a strong virus-specific immune response by inducing local inflammation and the cytokines necessary to invoke HPV-specific immunity. [ABSTRACT FROM AUTHOR]