Triptolide regulates T cell-mediated immunity via induction of CD11c(low) dendritic cell differentiation.

Triptolide(TPT) isolated from one of the Chinese herbs, Tripterygium wilfordii Hook. F. (TWHF), are known to have a variety of immunomodulatory activities. This study was performed to investigate the effect of TPT on the differentiation of splenic DCs and its influence on T cell-mediated immunity regarding to DC subsets CD11c(low)I-a/e(low)CD45RB(+)(CD11c(low) DCs) and CD11c(high)I-a/e(high)CD45RB(-) (CD11c(high) DCs) in male C57BL/6 mice spleens in vitro. The percentage of CD11c(low) DCs was significantly increased after treatment with TPT compared to their counterparts (CD11c(high) DCs). It was found that unlike the gradually decreasing interleukin (IL)-12 secretion of CD11c(high) DCs induced by TPT, CD11c(low) DCs showed a obvious dose-dependent response between the increasing of IL-10 production and TPT stimulation. After treatment with anti-IL-12R or anti-IL-10 monoclonal antibody in CD4(+) T cells+CD11c(high) DCs or CD11c(low) DCs mixed lymphocyte reaction, the induction of these DCs on T cells was inhibited dramatically. These data demonstrated that TPT might induce the differentiation of splenic DCs to CD11c(low) DCs followed by shifting of Th1 to Th2 with enhancement of T lymphocyte immune function in vitro.