Fig. 5.

IRF4 is important for IL-21-mediated Foxp3 suppression. Flow cytometry of naïve Irf4^−/− or WT CD4⁺ T cells differentiated as described in Fig. 1A and stained for intracellular Foxp3 (A) and of CD4⁺ WT cells nucleofected, cultured as described in Fig. 2B, and stained for Foxp3 (B). (A and B) Frequencies of Foxp3⁺ cells are indicated. (C) CD4⁺ T WT cells transduced with retroviruses expressing Foxp3-GFP or GFP, treated with IL-21 plus TGFβ, and stained for intracellular IL-17 or Foxp3. (Top) The percentages of GFP⁻IL-17⁺ (Left) or GFP⁺IL-17⁺ cells (Right) or the mean fluorescence intensity (MFI) of GFP⁻ or GFP⁺ cells stained for Foxp3 are indicated. Representative data from three experiments are shown.