Loss of Arid5a in T cells alters the character of inflammatory CD4⁺ T cells under Th17-polarizing conditions. (A) Quantitative real-time PCR analysis of Il17a mRNA in CD4⁺ WT or Arid5a-deficient T cells differentiated for 48 h in Th0, Th1, Th2, or Th17 cell conditions, normalized to the expression of Gapdh mRNA. (B) Level of IL-17 in the supernatants in CD4⁺ WT or Arid5a-deficient T cells differentiated for 72 h in Th0 or Th17 cell conditions by ELISA. (C) Frequency of IL-17–producing or IFN-γ–producing T cell population in WT or Arid5a-deficient CD4⁺ T cells differentiated for 72 h toward Th17 cells. (D) Proliferation of naive WT or Arid5a-deficient CD4⁺ T cells differentiated for 48 h toward Th17 cells. (E) Quantitative real-time PCR analysis of Ifnγ mRNA in CD4⁺ WT or Arid5a-deficient T cells differentiated for 48 h in Th0, Th1, Th2, or Th17 cell conditions, normalized to the expression of Gapdh mRNA. (F) Quantitative real-time PCR analysis of Tbx21 mRNA in CD4⁺ WT or Arid5a-deficient T cells differentiated for 48 h into Th0 or Th1 cells, normalized to the expression of Gapdh mRNA. (G) Level of IFN-γ in the supernatants in CD4⁺ WT or Arid5a-deficient T cells differentiated for 48 h in Th0 or Th17 cell conditions by ELISA. (H and I) Quantitative real-time PCR analysis of Gata3 or Il4 mRNA in CD4⁺ WT or Arid5a-deficient T cells differentiated for 72 h into Th0 or Th2 cells, normalized to the expression of Gapdh mRNA. (J) FACS analysis of IL-4 in CD4⁺ WT or Arid5a-deficient T cells differentiated for 96 h into Th2 cells. (K) FACS analysis of FoxP3 in CD4⁺ WT or Arid5a-deficient T cells differentiated for 48 h into T reg cells. (L and M) Quantitative real-time PCR analysis of Il10 or Maf mRNA in CD4⁺ WT or Arid5a-deficient T cells differentiated for 48 h in Th0 or Th17 cell conditions, normalized to the expression of Gapdh mRNA. Data are representative of three independent experiments (A–M). Error bars show mean ± SD (A, B, E–I, L, and M). *, P < 0.05; **, P < 0.02; ***, P < 0.001 (Student’s t test).