TGFβ-induced FOXP3 expression was stable and requires IL-2 or other common γ cytokines for maintenance. (A) Flow cytometric analyses of FOXP3 with 259D on TGFβ-treated CD45RA⁺ cells over a 30-day period in the presence of IL-2. (B) FOXP3 expression on TGFβ-treated CD45RA⁺ cells at day 7 and 48 hours later after cultured with IL-2 with or without anti-TGFβ or with neutralizing anti-IL2 mAb with or without IL-1β, TNFα, IFNγ, IL-4, IL-6, IL-7, IL-10, or IL-15. The MFI values are derived from the gating of the FOXP3⁺ population. Data above are representative of 3 independent experiments. Numbers in each quadrant as in Figure 1.