<Originals>Expression of the Th1 surface marker, Tim-3, on allergen-stimulated T cells of allergen-sensitve donors

publisher[Abstract] Background : The “Th2 hypothesis for asthma” remains controversial, because IFN-γ is not always suppressed in allergic asthma. Our objectives were therefore to identify the characteristics of IFN-γ-producing CD4^+ T cells that were induced by exposure to an allergen. Methods : Peripheral blood mononuclear cells (PBMC) were stimulated with house dust mites (HDM) and non-allergeic ubiquitous antigen M. tuberculosisPPD for 7 and 14 days, and then intracellular cytokines, IFN-γ and IL-4, and surface markers, Tim-3 and CRTH2, which were specifically identified in Th1 and Th2 cells, respectively, were quantified by flow cytometry. Results : We found that stimulation with HDM for 14 days generated IL-4- as well as IFN-γ-producing CD4^+ T cells (6.1±0.7％ and 24.0±6.2％, respectively). In addition, stimulation with HDM induced Tim-3 expression on IFN-γ-producing CD4^+ T cells and CRTH2 expression on IL-4-producing CD4^+ T cells (16.1±7.5％ vs. 0.9±0.5％ and 21.2±6.7％ vs. 9.6±4.7％, respectively, compared to no stimulation). On the other hand, very few IFN-γ- and IL-4-producing CD4^+ T cells stimulated with PPD expressedTim-3 and CRTH2. Conclusions : In vitro allergen-stimulated PBMCs contributed to the differentiation of Th2 as well as Th1 cells. A substantial fraction of Th1 cells expressed the expression of Tim-3, which is a death signal