Th17- and Th1-like Treg cells are phenotypically and functionally stable. (A) Quantitative RT-PCR analysis of RORγt (RORC), T-bet (TBX21), and FOXP3 (FOXP3) expression by the indicated Th and Treg cell subsets after 9 days of in vitro expansion. AU indicates arbitrary units. Data are means ± SEM of 4 donors. (B) Flow cytometric analysis of FOXP3, IFN-γ, IL-17, and IL-10 expression on expanded Th17- and Th1-like Treg cells stimulated for 5 hours with PMA/ionomycin. Data are representative of 4 independent experiments.