NKG2A and granzyme B distribution and responses of NK cells in vivo and in vitro. (A) Distribution of NK cell subsets in AML patients before treatment start (n = 64) and in healthy donors (n = 24). Frequency of NKG2A⁺ NK cells in subsets expressing 0, 1, 2, or 3 KIRs in AML patients (n = 54) before or after cycle 1 (B) and in unstimulated and IL-2–stimulated (500 U/ml) healthy donors (n = 6) (C). (D) Fold change, compared with start, in messenger RNA expression of NKG2A after IL-2 stimulation. (E) Granzyme B expression (median fluorescence intensity [MFI]) in unstimulated and IL-2–stimulated NK cell subsets (n = 24). (F) Percentage increase in granzyme B response between unstimulated and IL-2–stimulated NK cells (n = 24). (G) LFS for patients dichotomized by median NKG2A expression at treatment start (low, n = 29 or high, n = 30). (H) LFS for patients dichotomized by median frequency of NKG2A⁺ NK cells (low, n = 29 or high, n = 30). *P < .05, **P < .005, ***P < .0005.