CMV induces expansion of NK cells expressing a clonal pattern of self-specific KIRs. (A) Representative plot of KIR2DL1 and KIR2DL3 expression in NKG2C^-NKG2A^- (top) and NKG2C⁺ (bottom) CD56^dim NK cell subsets. Three CMV-seropositive donors with different HLA genotypes are depicted. The color-coding pairs KIRs with their cognate HLA ligands. (B) Shown are 2 extreme examples of KIR repertoires in CMV-seropositive donors (C2/C2 blue and C1/C1 red) overlaid on the 48 KIR repertoires from CMV-seronegative individuals (n = 48). (C) The aggregated effect of the HLA-C genotype on KIR expression in all donors was examined by plotting frequencies of KIR2DL1 and KIR2DL3 in NKG2A⁺ (left), NKG2C^-NKG2A^- (middle), and NKG2C⁺ (right) NK cell subsets, respectively. Donors were stratified based on CMV serology and HLA background. (D) The effect of HLA-C genotype on self-specific KIR expression in CMV-seropositive individuals with and without evidence of NK cell expansion.