Expansion potential of human CD8⁺ T-cell subsets following cytokine or TCR stimulation. (A) Naive, central memory (T_CM), effector memory (T_EM), and CD45RA⁺ effector memory (T_EMRA) cells were isolated from peripheral blood according to the expression of CCR7 and CD45RA, labeled with CFSE, and cultured with allogeneic mature DCs (mDCs) or stimulated with 25 ng/mL IL-7 and IL-15. Cell division was measured after 7 days. Dotted line indicates CFSE intensity of undivided cells. One representative experiment of 4 is shown. (B) Purified, CFSE-labeled T_CM and T_EM cells were stimulated with 25 ng/mL IL-21, 10³ U/mL IL-2, 10 ng/mL IL-7 and IL-15 in the absence or presence of 103 U/mL IL-2, 2 μg/mL anti–IL-2, or 10 ng/mL IL-6 and IL-10. Proliferation was assessed by flow cytometry on day 7. The dotted line indicates the number of input cells. Number of viable cells (C) and percentage of dead (propidium iodide⁺) cells (D) recovered on day 7 after stimulation with allogeneic mDCs (□) or IL-7 and IL-15 (▪). Mean of 4 independent experiments.