Determination of interleukin‐5 secretion from drug‐specific activated ex vivo peripheral blood mononuclear cells as a test system for the in vitro detection of drug sensitization

Summary BackgroundIn vitro detection of drug sensitization is still limited. The lymphocyte transformation test, which determines drug-specific proliferation, is the only in vitro test for detecting drug sensitization at the cellular level irrespective of the reaction's clinical phenotype. Accumulation of eosinophils following IL-5 secretion from drug-specific stimulated T cells is a characteristic histological feature of drug-induced skin eruptions. Objective We determined whether in vitro drug-specific activation of ex vivo peripheral blood mononuclear cells from 10 patients with drug-induced maculopapular exanthems and three patients with severe skin reactions results in secretion of IL-5, IL-10 or IFN-γ and assessed the sensitivity and specificity of drug-specific IL-5 secretion as a test system compared with the lymphocyte transformation test and patch tests. Furthermore, the subsets of CD4+ and CD8+ T cells involved in drug-specific proliferation, IL-5 secretion and mRNA expression were examined in three patients. Methods Drug-specific proliferation of peripheral blood mononuclear cells in the lymphocyte transformation test was investigated by 3H-thymidine uptake, and culture supernatants taken after 5 days were analysed for IL-5, IL-10 and IFN-γ concentrations by ELISA technique. IL-5 mRNA expression was determined by RT-PCR. Results Drug-specific activation of peripheral blood mononuclear cells consistently resulted in IL-5 and to a lesser extent in IL-10 and IFN-γ secretion. The sensitivities of the patch test, lymphocyte transformation test and assessment of drug-specific IL-5 secretion for the detection of drug sensitization were 55%, 75% and 92%, respectively. Conclusion These data suggest a role for the determination of drug-specific IL-5 secretion by ex vivo peripheral blood mononuclear cells for the in vitro detection of drug-sensitization in drug-induced maculopapular exanthems.