A selective inhibition of ADAM17 reduces cytokine-induced shedding of CD16 and CD62L. Purified NK cells (n = 8) were incubated overnight in either media alone or with IL-12 and IL-18, with (white bars) or without (black bars) the addition of BMS566394 (10 μM). The percentage of CD16-positive cells (left) and mean fluorescent intensity (MFI) (right) was determined for CD56^dim NK cells (A), the percentage of CD62L-expressing cells was determined for CD56^bright (left) and CD56^dim (right) NK cells (B), and intracellular IFN-γ levels for CD56^dim NK cells was measured by flow cytometry (C). Bars represent mean ± SEM. NK cells were compared with NK cells incubated with BMS566394 using the paired t test. (D) Purified NK cells (n = 4) were incubated overnight in either media alone (light gray bars) or with IL-12 and IL-18 (dark gray bars), in the presence of the BMS566394 (ADAM17 inhibitor) (10 μM) or D1(A12) (ADAM17 inhibitory antibody) (6 μg/mL). Bars represent mean ± SEM of CD56^dim NK cells expressing CD16 at baseline or with cytokine activation with or without the ADAM17 inhibition method indicated on the x-axis. NK cells incubated in media alone were compared with NK cells incubated with IL-12 and IL-18 using the paired t test. Statistical significance is indicated as: *P ≤ .05; **P < .01; ***P < .001.