Fig. 4.
Tumor-secreted TGF-β inhibited Th17 cell expansion but promoted Treg cells. (A) Ovarian tumor cells secrete latent (inactive) and active TGF-β in culture. Cell supernatants were harvested and used to determine the concentration of TGF-β by ELISA according to the manufacturer's instructions. (B) TGF-β inhibits the expansion of Th17 cells by other cytokines. The purified human CD4+ T cells were stimulated with plate-bound OKT3 in the presence of the indicated cytokines, either alone or in various combinations, in T cell medium. Ten days after activation, the cells were restimulated with PMA/ionomycin and subjected to intracellular cytokine staining. The percentages of IL-17 expressing T cells in T cell medium served as a baseline. The data represent one of two independent experiments. (C) TGF-β inhibits the expansion of IL-17-producing T cells in a dose-dependent manner. Memory T cells were cultured in the presence of plate-bound OKT3 in the presence of the indicated concentrations of TGF-β. Results for the purified memory T cells of three healthy donors are plotted as mean ± SD value. *, P <0.05. (D) TGF-β promoted the generation of Foxp3+ T cells, but this effect was blocked by IL-6. The purified human CD4+ T cells were stimulated with plate-bound OKT3 in the presence of TGF-β either alone or in various combinations with other cytokines. Ten days after activation, the cells were analyzed for Foxp3 expression after intracellular cytokine staining with anti-Foxp3.