Figure 5.

Low levels of caspase activity in homeostatically proliferating, regulatory, naive, and memory T cells. (a) Caspase activity of T cells undergoing homeostatic expansion (HP) was compared with day 5 IL-2- or IL-15-cultured T cells and freshly isolated naive (CD44^low) T cells. Homeostatically proliferating T cells were generated through adoptive transfer of wild-type lymphocytes into Rag1^−/− mice and on day 14, donor CD4⁺ and CD8⁺ T cells were purified from Rag1^−/− mice by cell sorting. (b and c) Freshly isolated CD4⁺ T cells from FoxP3^GFP mice were sorted for FoxP3⁻ and FoxP3⁺ cells and their caspase activity was compared with day 5 IL-2-cultured T cells. Numbers in flow cytometry quadrants indicate the percent positive cells. (d and e) Freshly isolated T cells from wild-type mice were sorted for CD4⁺CD44^high, CD4⁺CD44^low, CD8⁺CD44^high, and CD8⁺CD44^low cells and their caspase activity was compared with day 5 IL-2-cultured T cells