NK cells express ADAM17. Surface expression of ADAM17 was assessed on different lymphocyte subsets. (A) ADAM17 expression was measured on CD56⁺CD3^- NK cells from 4 healthy donors. (B) ADAM17 mean fluorescent intensity (MFI) was compared between CD56^bright, CD56^dim, CD3⁺CD56⁺ and CD3⁺CD56^-lymphocytes (n = 4). Bars represent mean ± SEM. Subsets were compared with total NK cells using the paired t test. Statistical significance is indicated as: *P ≤ .05; **P < .01; ***P < .001. NS, nonsignificant.