Quantitative and functional reconstitution of NK-cell subsets after allogeneic HSCT. (A) Absolute cell numbers in each subset were determined by flow cytometry. (B) NK-cell responsiveness was assessed as the percentage of CD107a⁺ cells in each NK-cell subset after a 15-hour incubation with K562 targets. *P < .05; **P < .01; ***P < .001.