[Dexamethasone-induced apoptosis in peripheral T lymphocytes from patients with asthma].

The corticosteroid is effective for treating allergic inflammation. However, the mechanisms of the effectiveness are still unclarified. In this study, we examined whether dexamethasone, one of corticosteroids, can induce apoptosis in peripheral T cells from patients with asthma. Dexamethasone induced significantly greater apoptosis in T cells from patients with asthma than from normal subjects at 10(-4) M and 10(-5) M (p < 0.05). Apoptosis was assessed by flow cytometry, DNA fragmentation. By examining the function of T cell subsets, the augmentation of apoptosis was ascribed to CD4+HLADR+CD25+subsets. Elimination of HLADR+CD25+subsets from T cells caused a great reduction in IL-5 production and proliferation to mite on Day 3, suggesting that the subset might be primed by mite allergen. Dexamethasone may reduce allergen specific T cells through apoptosis, which is one of the mechanisms of effectiveness of dexamethasone in asthmatics.