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Drug hypersensitivity reactions have multiple implications for patient safety and health system costs, thus it is important to perform an accurate diagnosis. The diagnostic procedure includes a detailed clinical history, often unreliable; followed by skin tests, sometimes with low sensitivity or unavailable; and drug provocation testing, which is not risk-free for the patient, especially in severe reactions. In vitro tests could help to identify correctly the responsible agent, thus improving the diagnosis of these reactions, helping the physician to find safe alternatives, and reducing the need to perform drug provocation testing. However, it is necessary to confirm the sensitivity, specificity, negative and positive predictive values for these in vitro tests to enable their implementation in clinical practice. In this review, we have analyzed these parameters from different studies that have used in vitro test for evaluating drug hypersensitivity reactions and estimated the added value of these tests to the in vivo diagnosis. [ABSTRACT FROM AUTHOR]

Key points: Intranasal allergen exposure increases peripheral total Th2 and Th9 cells in patients with local allergic rhinitis (LAR).Peripheral T‐cell response seems dominated by Th9 cells in patients with LAR, whereas Th2 responses prevail in patients with allergic rhinitis.Our results identify Th9 cells as potential therapeutic targets for patients with LAR. [ABSTRACT FROM AUTHOR]

Background: Immediate drug hypersensitivity reactions (IDHRs) to clavulanic acid (CLV) have increased in the last decades due to a higher consumption alongside amoxicillin (AX). Due to its chemical instability, diagnostic procedures to evaluate IDHRs to CLV are difficult, and current in vitro assays do not have an optimal sensitivity. The inclusion of the specific metabolites after CLV degradation, which are efficiently recognised by the immune system, could help to improve sensitivity of in vitro tests. Methods: Recognition by dendritic cells (DCs) of CLV and the synthetic analogues of two of its hypothesised antigenic determinants (ADs) was evaluated by flow cytometry in 27 allergic patients (AP) and healthy controls (HC). Their ability to trigger the proliferation of T cells was also analysed by flow cytometry. Results: The inclusion of synthetic analogues of CLV ADs, significantly increased the expression of maturation markers on DCs from AP compared to HC. A different recognition pattern could be observed with each AD, and, therefore, the inclusion of both ADs achieves an improved sensitivity. The addition of synthetic ADs analogues increased the proliferative response of CD4+Th2 compared to the addition of native CLV. The combination of results from both ADs increased the sensitivity of proliferative assays from 19% to 65% with a specificity higher than 90%. Conclusions: Synthetic ADs from CLV are efficiently recognised by DCs with ability to activate CD4+Th2 cells from AP. The combination of analogues from both ADs, significantly increased the sensitivity of DC maturation and T‐cell proliferation compared to native CLV. [ABSTRACT FROM AUTHOR]

The immunological mechanisms involved in drug hypersensitivity reactions (DHRs) are complex, and despite important advances, multiple aspects remain poorly understood. These not fully known aspects are mainly related to the factors that drive towards either a tolerant or a hypersensitivity response and specifically regarding the role of B and T cells. In this review, we focus on recent findings on this knowledge area within the last 2 years. We highlight new evidences of covalent and non‐covalent interactions of drug antigen with proteins, as well as the very first characterization of naturally processed flucloxacillin‐haptenated human leukocyte antigen (HLA) ligands. Moreover, we have analysed new insights into the identification of risk factors associated with the development of DHRs, such as the role of oxidative metabolism of drugs in the activation of the immune system and the discovery of new associations between DHRs and HLA variants. Finally, evidence of IgG‐mediated anaphylaxis in humans and the involvement of specific subpopulations of effector cells associated with different clinical entities are also topics explored in this review. All these recent findings are relevant for the underlying pathology mechanisms and advance the field towards a more precise diagnosis, management and treatment approach for DHRs. [ABSTRACT FROM AUTHOR]

T cells are known to develop a critical role in the pathogenesis of atopic dermatitis (AD) and bronchial asthma. T cells involved in AD express the skin homing receptor CLA, but no lung homing receptor has been identified in bronchial asthma. We compared different cell markers and the cytokine production in T cells from children with AD or bronchial asthma. We studied the involvement of CLA+ and CLA− T-cell subpopulations in these diseases. We studied 20 children with acute AD lesions, 15 with mild persistent asthma, and 15 non-atopic controls. All patients were sensitized to house dust mite (DP) and evaluated during the acute phase. Total and specific IgE were measured by immunoassay and the expression of different cell markers and the cytokine production was analyzed by flow cytometry in peripheral blood mononuclear cells. Total IgE was significantly higher in AD children and IgE to DP in the asthmatic children. There was a significant increase in CD25+CD4+ cells in asthmatic children and in HLA-DR+CD4+ and HLA-DR+CD8+ cells in AD. In the CD4+ subsets, there was an increase in IL-13, IL-5 and TNF- α in AD compared to controls, a decrease in IFN- γ in asthmatic children compared to controls, and an increase in IL-13, IL5, IL2, TNF- α, and IFN- γ in the AD compared to asthmatic children. Changes in cytokine production were mainly detected in CLA+ cells in AD and in CLA− cells in asthma. Differences exist in total and specific IgE, activation markers, and cytokine patterns between AD children and children with asthma, with the former expressing a Th2 pattern whereas in asthmatic children we only detected a decrease in IFN- γ. Moreover, the subpopulations (CLA+ vs. CLA−) expressing these changes were different, indicating that the underlying mechanisms in the two diseases are not exactly the same. [ABSTRACT FROM AUTHOR]

ABSTRACTDrugs can induce IgE mediated or T cell dependent immunological reactions. T cell dependent reactions are poorly understood, although T lymphocytes have been proposed as a protagonist in a number of non-immediate immunological reactions (NIR). The objective was to study in vivo different regulatory and proinflammatory cytokines and cytotoxic markers in patients with NIR to drugs. Twenty patients with NIR after drug intake were classified into two groups: Group A (severe), Stevens–Johnson syndrome and toxic epidermal necrolysis; and Group B (mild), maculopapular exanthema and desquamative exanthema. Another 25 subjects taking the same drugs but without reactions formed a control group. Samples were obtained within 24 hours of the reaction and 30 days later. IL-2, IL-4, IFN, TNF, perforin, granzyme B (GrB), and FasL mRNA expression levels were determined in peripheral blood mononuclear cells by competitive RT-PCR. There were 9 patients in Group A and 11 in Group B. The drugs involved were betalactams (8), anticonvulsants (6), allopurinol (1), sulfamethoxazole (1), amiodarone (1) dypirone (2), and erythromicine+paracetamol (1). At the acute stage there was a high increase of IL-2, IFN, and TNF mRNA expression in both groups vs. controls, perforin and GrB varied in each group with patients in Group A having the highest values, and FasL was only expressed in Group A. Relationships between the cytokines were only significant in Group B (p < 0.05). Only the relation between IFN-γ and TNF-α was significant in Group A. There was a significant correlation between cytotoxic markers in both groups (A: p < 0.001, B: p < 0.01). These data demonstrate the complexity of the Th1 phenotype in NIR after drug intake. In patients with mild NIR, cytokines appear to play a closely related role, whereas cytotoxic markers appear more relevant in severe reactions. [Copyright &y& Elsevier]

Background: Drug‐induced maculopapular exanthemas (MPEs) are mediated by Th1 CD4+ T cells. One of the mechanisms of control of Th1 cells in homeostasis is the interaction between the checkpoint inhibitor Tim3 and its physiological ligand galectin‐9 (Gal9). Disorders affecting this axis may be responsible for various autoimmune and immunological diseases. The aim of this study was to determinate the influence of the Tim3‐Gal9 axis on the development of MPE induced by drugs. Methods: Frequencies of different cell subsets and the expression of Tim3 and Gal9 were measured in peripheral blood by flow cytometry and in skin biopsies by immunohistochemistry. Gal9 expression was assessed by RT‐qPCR; its release was measured by multiplex assay. The effects of blocking or enhancing the Tim3‐Gal9 axis on monocyte‐derived dendritic cell (moDC) maturation and T‐cell proliferation were determined by flow cytometry. Results: The expression of Tim3 was significantly reduced in peripheral blood Th1 cells and in the skin of MPE patients vs controls. Gal9 expression and release were significantly reduced in patient peripheral blood and moDCs, respectively. The addition of exogenous Gal9 significantly reduced Tim3+ Th1 proliferation, although Treg proliferation increased. Conclusion: This study showed the involvement of the Tim3‐Gal9 axis in MPE. The reduced expression of Tim3 in Th1 cells together with the impaired expression of Gal9 in PBMCs and DCs appears to have a role in the development of the disease. The potential of Gal9 to suppress Th1 and enhance Treg proliferation makes it a promising tool for treating these reactions. [ABSTRACT FROM AUTHOR]

The mechanisms leading to drug allergy in predisposed patients, especially those related to T-cell-mediated drug hypersensitivity, are not well understood. A key event in allergic reactions to drugs is the maturation process undergone by dendritic cells (DCs). Although amoxicillin (AX) has been reported to interact and maturate DCs from patients with AX-induced delayed-type hypersensitivity, the cell signaling pathways related to AX-mediated DC maturation have not been elucidated. We sought to determine the role of the MAPK and NF-κΒ pathways on AX-induced DC maturation and functional status. For that purpose, in monocyte-derived-DCs from AX-delayed allergic patients and tolerant subjects, we analyzed the activation pattern of p38MAPK, JNK, and ERK signaling and the NF-κB, maturation markers as well as endocytosis and allostimulatory capacities driven by AX-stimulated-DCs. Our data reveal that AX induces an increase in the phosphorylation levels of the three MAPKsand activated NF-κB in DCs from allergic patients. Moreover, the inhibition of these pathways prevents the up-regulation of surface molecules induced by AX. Additionally, we observed that the allostimulatory capacity and the endocytosis down-regulation in AX-stimulated-DCs from allergic patients depend on JNK and NF-κB activities. Taken together, our data shed light for the first time on the main signaling pathways involved in DC maturation from AX-delayed allergic patient. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) have been suggested for immunotherapy applications in order to optimize the delivery of immuno-stimulative or -suppressive molecules. However, low attention towards the impact of the NPs' physicochemical properties has presented a major hurdle for developing efficient immunotherapeutic agents. Here, the effects of porous silicon (PSi) NPs with different surface chemistries were evaluated on human monocyte-derived dendritic cells (MDDCs) and lymphocytes in order to highlight the importance of the NPs selection in immuno-stimulative or -suppressive treatment. Although all the PSi NPs showed high biocompatibility, only thermally oxidized PSi (TOPSi) and thermally hydrocarbonized PSi (THCPSi) NPs were able to induce very high rate of immunoactivation by enhancing the expression of surface co-stimulatory markers of the MDDCs (CD80, CD83, CD86, and HLA-DR), inducing T-cell proliferation, and also the secretion of interleukins (IL-1β, IL-4, IL-6, IL-10, IL-12, IFN-γ, and TNF-α). These results indicated a balanced increase in the secretion of Th1, Th2, and Treg cytokines. Moreover, undecylenic acid functionalized THCPSi, as well as poly(methyl vinyl ether-alt-maleic acid) conjugated to (3-aminopropyl)triethoxysilane functionalized thermally carbonized PSi and polyethyleneimine conjugated undecylenic acid functionalized THCPSi NPs showed moderate immunoactivation due to the mild increase in the above-mentioned markers. By contrast, thermally carbonized PSi (TCPSi) and (3-aminopropyl)triethoxysilane functionalized TCPSi NPs did not induce any immunological responses, suggesting that their application could be in the delivery of immunosuppressive molecules. Overall, our findings suggest all the NPs containing more nitrogen or oxygen on the outermost backbone layer have lower immunostimulatory effect than NPs with higher C–H structures on the surface. [ABSTRACT FROM AUTHOR]

Amoxicillin, a low-molecular-weight compound, is able to interact with dendritic cells inducing semi-maturation in vitro. Specific antigens and TLR ligands can synergistically interact with dendritic cells (DC), leading to complete maturation and more efficient T-cell stimulation. The aim of the study was to evaluate the synergistic effect of amoxicillin and the TLR2, 4 and 7/8 agonists (PAM, LPS and R848, respectively) in TLR expression, DC maturation and specific T-cell response in patients with delayed-type hypersensitivity (DTH) reactions to amoxicillin. Monocyte-derived DC from 15 patients with DTH to amoxicillin and 15 controls were cultured with amoxicillin in the presence or absence of TLR2, 4 and 7/8 agonists (PAM, LPS and R848, respectively). We studied TLR1-9 gene expression by RT-qPCR, and DC maturation, lymphocyte proliferation and cytokine production by flow cytometry. DC from both patients and controls expressed all TLRs except TLR9. The amoxicillin plus TLR2/4 or TLR7/8 ligands showed significant differences, mainly in patients: AX+PAM+LPS induced a decrease in TLR2 and AX+R848 in TLR2, 4, 7 and 8 mRNA levels. AX+PAM+LPS significantly increased the percentage of maturation in patients (75%) vs. controls (40%) (p=0.036) and T-cell proliferation (80.7% vs. 27.3% of cases; p=0.001). Moreover, the combinations AX+PAM+LPS and AX+R848 produced a significant increase in IL-12p70 during both DC maturation and T-cell proliferation. These results indicate that in amoxicillin-induced maculopapular exanthema, the presence of different TLR agonists could be critical for the induction of the innate and adaptive immune responses and this should be taken into account when evaluating allergic reactions to these drugs. [ABSTRACT FROM AUTHOR]