Reciprocal expression of NKG2A and KIR in different groups of patients undergoing UCBT. Peripheral blood NK cells were analyzed by FACS for the expression of NKG2A in combination with KIRs at 1, 3, 6, and 12 months after transplantation. (A) Three patients representative of the different groups are shown. The percentage of NKG2A⁺KIR⁻, NKG2A⁺KIR⁺, and NKG2A⁻KIR⁺ NK-cell subsets are indicated in the corresponding quadrants at each time point. (B) For comparison, NKG2A in combination with KIRs is shown for 2 representative healthy donor NK cells (middle and right) and for CB NK cells (left). (C) The percentage of KIR⁺NKG2A⁻ and (D) the percentage of NKG2A⁺ CD56^dim NK cells are shown as 95% CI for the mean at the different time points (top, group 1 ●; middle, group 2 ■; bottom, group 3 ▴). (C-D) The 95% CI for the mean is reported for healthy adult (□) and CB (○) NK-cell subsets in each panel.