Effect of cytokine-activated, sorted NK-cell subsets on PMN survival and activation. CD56^dim (dim) and CD56^bright (br) NK cells were sorted by FACS and stimulated with either IL-2 or a combination of IL-12 and IL-18. PMNs were then cultured in the absence or presence of supernatants from unstimulated or cytokine-activated and sorted NK-cell subsets for 18 to 24 hours and compared with control medium (Med) and PMNs treated with cytokines alone. The percentage of apoptotic PMNs cultured in the absence or presence of supernatants from (A) IL-2 (n= 4) or (B) IL-12 plus IL-18 (n= 4) activated CD56^dim and CD56^bright NK cells. Evaluation of CD11b surface expression on PMNs in the absence or presence of (C) IL-2 (n= 4) or (D) IL-12 plus IL-18 (n= 4) activated CD56^dim and CD56^bright NK-cell supernatants. Expression of CD62L on the surface of PMNs when cultured in the absence (Med) or presence of (E) IL-2 (n= 4) or (F) IL-12 plus IL-18 (n= 4) activated CD56^dim and CD56^bright NK-cell supernatants. Results are expressed as mean ± SEM. *P < .05; **P < .01; ***P < .001.