Expression of activation markers on PMNs when cultured with supernatants from cytokine-activated NK cells. Representative histograms of (A) CD11b and (B) CD62L expression on PMNs when cultured in the absence (dotted profile) or presence (solid profile) of cytokine-activated NK-cell supernatant. Matched isotype controls are shown by the shaded profile. Mean fluorescence intensity (MFI) is indicated. Quantitative representation of the mean fluorescence intensity of (C) CD11b and (D) CD62L on the surface of PMNs when cultured alone (Med) or with supernatants from unstimulated (NK sup) or IL-2–activated (NK + IL-2 sup) NK cells for 18 to 24 hours, from 24 individual experiments. Evaluation of (E) CD11b and (F) CD62L surface expression on PMNs when cultured with supernatants from NK cells stimulated with IL-2, IL-21, IL-15, IL-12, IL-18, or a combination of IL-12 plus IL-18 compared with control medium (Med) and PMNs treated with cytokines alone (n= 5). The results are expressed as mean ± SEM. **P < .01; ***P < .001.