Acquired down-regulation of the response to TCR signaling in CD161^hi CD62L⁺ and CD62L⁻ memory CD8α⁺ T-cell subsets. (A) The FACS plot (left) is gated on CD95⁺ memory CD8α⁺ TcRαβ⁺ T cells and quadrants indicate high versus intermediate/absent expression of CD161. The graph (right) shows the percentages of CD161^hi cells within the CD62L⁺ and CD62L⁻ memory subsets. Horizontal bars represent the mean ± SE of experiments in 57 individuals. (B) Sort-purified adult memory subsets were cultured with αCD3 for 72 hours before assessment of proliferation by tritiated thymidine incorporation. Data are representative of the mean ± SE of 13 separate experiments. (C) UCB CD161^hi cells were cultured alone (Nil) or with αCD3 for 72 hours before assessment of proliferation by tritiated thymidine incorporation. Data are representative of the mean ± SE of 4 separate experiments. (D-E) Sort-purified subsets were stimulated with αCD3 (D) or PMA/ionomycin (E) and cytokine concentrations were assessed in the supernatant 18 hours later. Data represent the mean ± SE of at least 4 separate experiments.