Exogenous IL-2 recovers the decreased Treg but not T_H17 generation by 1,25(OH)₂D₃.

<p>Naïve CD4⁺ T cells from Rag2^−/− DO11.10 mice (BALB/c background) were cultured with 0.25 µM OVA_323–339 peptide in the presence of CD3⁺ T cell-depleted splenocytes for 4 days. (<b>A</b>) Under Treg-polarizing conditions with 1,25(OH)₂D₃ (0.1, 1, 10, and 100 nM), culture supernatants were analyzed for IL-2 production by ELISA. (<b>B</b>) Under Treg-polarizing conditions, IL-2 cytokine was added in 1,25(OH)₂D₃-treated groups in a dose-dependent manner (IL-2: 0.1, 1, 10, and 20 ng/ml); 4 days later the CD4⁺ T cells were stained intracellularly for Foxp3. (<b>C</b>) Under T_H17-polarizing conditions, 1,25(OH)₂D₃ (100 nM) and IL-2 (0.1, 1, 10, and 20 ng/ml) were added. The average frequency of IL-17A⁺ T cells in gated CD4⁺KJ1-26⁺ cells is shown. Means ± SD of triplicate samples are plotted. Data are representative of three independent experiments with at least three mice per group. *p<0.05, ***p<0.001 compared with cytokine-alone group.