CD161+ regulatory T cells and cytokine-producing phenotype persist upon Treg expansion. Treg expansion over 10 days with or without cytokine treatment (n = 4). (A) Representative flow cytometry plots of FoxP3 expression at day 10 with stimulation alone for CD161– and CD161+ cells (left), summary plots for FoxP3 expression overall (middle), and frequency of CD161 in FoxP3+ cells (right). Horizontal lines represent the median; diamonds, stimulation alone; crosses, +IL-12; and triangles, +TGF-β, IL-1β, and IL-23. (B) Representative flow cytometry plots showing cytokine production (IL-17A vs IFN-γ) of CD161–FoxP3+ (left) and CD161+FoxP3+ cells (right) with summary plots showing mean ± SEM for IL-17A single-, IFN-γ single-, and IL-17A+IFN-γ double-producing cells for CD161– (white bars) and CD161+FoxP3+ (black bars).