Degranulation and cytotoxicity by T-cell and NK cell subsets. (A-B) Freshly isolated, resting PBMCs from healthy adult volunteers were incubated alone or mixed with target cells and mAbs, as indicated, at 37°C for 2 hours. Thereafter, cells were surface stained with fluorochrome-conjugated antibodies to CD3, CD4, CD8, CD56, CD57, and CD107a. (A) Contour plots of CD57 versus CD107a staining on CD8⁺ T-cell and CD3⁻CD56⁺ NK cell subsets after the indicated target cell stimulations. Plots with concatenated data from 6 representative donors are shown. Numbers indicate the percentages of degranulating CD57⁻, CD57^dim, and CD57^bright cells. (B) Induced CD107a surface (ΔCD107a⁺) expression on T-cell and NK cell subsets after 2 hours of target cell stimulations, as indicated. Values represent the means ± SD of 14 donors. (C) CD3⁺CD8⁺ T-cell subsets, as specified, or CD3⁻CD56⁺ NK cells were isolated by negative selection. Effector cells were then incubated with target cells, as indicated, for 4 hours. Specific lysis was calculated. Values represent the means ± SD of at least 4 donors. Statistical analyses were performed using the Wilcoxon signed-rank matched pairs test. *P < .05; **P < .01; ***P < .001.