Vitamin D receptor on CD4⁺ T cells is required for regulation of Treg and T_H17 differentiation by 1,25(OH)₂D₃.

<p>Purified naïve CD4⁺ T cells from wild-type (WT) or VDR^−/− (KO) mice of B6 background were cultured with APCs from WT or VDR^−/− mice in the presence of 1 µg/ml anti-CD3 mAb for 4 days under Treg-polarizing conditions (rTGF-β, 1 ng/ml; anti-IFN-γ, 10 µg/ml; and anti-IL-4, 10 µg/ml) or T_H17-polarizing conditions (rTGF-β, 1 ng/ml; rIL-6, 20 ng/ml; anti-IFN-γ, 10 µg/ml; and anti-IL-4, 10 µg/ml). (<b>A</b>) Foxp3 expression in gated CD3⁺CD4⁺ cells was analyzed by flow cytometry. (<b>B</b>) For the IL-17A staining, CD4⁺ T cells were restimulated with PMA/ionomycin for 5 hr. Numbers beside quadrants indicate percentages of positive cells in each quadrant. Data are representative of three independent experiments with at least three mice per group. ***p<0.001 compared with cytokine-alone group.