Donor-HLA–determined NK-cell education pattern after KIR ligand–mismatched HSCT. The percentages of CD107a⁺ and/or IFNγ⁺ monoKIR NK cells were determined after incubation with K562 targets in samples from 26 post-HLA-C–mismatched transplantations (12 C1/C1→C1/C2, 7 C1/C2→C1/C1, 3 C1/C2→C2/C2, 4 C2/C2→C1/C2). (A) A representative labeling experiment is shown for each HSCT setting. (B) In recipients whose donor was homozygous, monoKIR NK-cell responsiveness was compared between cells expressing a receptor for donor self-HLA (CD158b for C1/C1 donors, CD158a for C2/C2 donors) and for donor nonself HLA (CD158a for C1/C1 donors, CD158b for C2/C2 donors). (C) The responsiveness of (left) CD158a monoKIR and (right) CD158b monoKIR NK cells was compared between recipients as a function of donor HLA-C genotype. When several samples were available for the same recipient, only the latest was included in the analysis. All dot plots were gated on total NK cells. Horizontal bars indicate the medians. *P < .05; **P < .01; ***P < .001.