IL-17A inhibits Th1 differentiation by preventing T-bet expression.

<p>Naive CD4+ T cells (10⁵) were sorted from B6 mice and stimulated for 96 hours with either syngeneic (B6) or allogeneic (bm12) T cell depleted spleen cells (4.10⁵). When indicated, recombinant mouse IL-17A was added in culture wells at 40 ng/ml. (<b>A</b>) The IFN-γ concentration was measured in supernatants by ELISA and the mean ± SEM of quintuplicates are shown. One representative experiment of two is shown (<b>B</b>) The percentages of T-bet+ cells among responder CD4+ T cells were determined by intracellular staining. The mean of triplicates is represented and one representative experiment of two is shown.