Pattern of inhibitory receptor expression on CD3^-CD56⁺NK cells after haploidentical SCT. (A) PB from donor and patient (no. 9) after SCT was stained with various inhibitory receptors: KIR2DL1 (CD158.a ▪), KIR2DL2 (CD158.b ▦), KIR3DL1 (CD158.e ▨), and CD94/NKG2A (□). Percentage of CD3^-CD56⁺ cells positive for those receptors are represented from day 15 to day 90 and compared with donor. Days after transplantation are indicated. (B) Expression of KIR2DL1 (CD158.a) and CD94/NKG2A on NK cells from donor and patient (no. 9) after SCT. Flow cytometric density plots and histograms are gated on CD3^-CD56⁺ NK cells. (C) Evolution of the putative alloreactive NK subset after SCT compared with the donor. Results obtained in the donor (▪) and in patient no. 9 at the engraftment (▨), day 30 (□), and day 90 (▦) after SCT are shown. The alloreactive NK subset was analyzed by 4-color flow cytometry expressed KIR2DL1 but not KIR3DL1 or KIR2DL2 or CD94/NKG2A. Results are expressed as the percentages of the alloreactive NK subset in the total NK population.