CCR4 expression discriminates Tc2 cells and CTL precursors among central memory CD8⁺ T cells. (A) IL-4 and IL-13 production by CD8⁺ T-cell subsets following stimulation with PdBu and ionomycin for 24 hours (▪) or IL-7 and IL-15 for 7 days (□). Mean of 5 independent experiments. (B) CCR7 and CCR4 expression by proliferating CFSE-labeled naive T cells stimulated by allogeneic mDCs in the presence of 10 ng/mL IL-4 or IL-12 and by freshly isolated CD45RA–CD8⁺ T cells. (C) Cytokine production by freshly isolated CCR4⁺ (▪) and CCR4^– (▧) central memory CD8⁺T cells following stimulation with PdBu and ionomycin. Mean of 3 independent experiments. (D) Cytokine-stimulated CCR4⁺ and CCR4–CD8 T_CM cells were analyzed on day 7 for the acquisition of perforin and CCR7 expression. One representative experiment of 3 is shown.