Phenotypic changes in murine Tregs after IL-2 therapy. Wild-type C57BL/6 mice received control vehicle or 5000 IU human recombinant IL-2 subcutaneously once per day for 14 days and spleen cells were analyzed on day 15. (A) Representative panels identify CD44^lowCD62L^high naïve (N), CD44^highCD62L^high central-memory (CM), and CD44^highCD62L^low effector-memory (EM) subsets within CD8 T cells, Tcons, and Tregs. (B) Percentage of each subset in CD8 T cells, Tcons, and Tregs after in vivo treatment with control vehicle or IL-2. (C) Representative flow cytometry histograms identifying PD-1⁺ cells in each T-cell subset after treatment with control vehicle or IL-2. (D) Percentage of PD-1⁺ cells in CD8 T cells, Tcons, and Tregs after treatment with control vehicle or IL-2. (E) Representative flow cytometry histograms detecting expression of CTLA-4, LAG-3, Tim-3, and PD-1 on CD8 T cells, Tcons, and Tregs with 4 mice per group per experiment. Data are representative of 3 independent experiments and expressed as means +/– SEM. ***P < .001 and ****P < .0001.