All combinations of inhibitory MHC class I receptors are represented in human NK-cell repertoires. In the upper part of the figure, the gray bars give the frequencies for CD56^dim NK cells having the receptor combination denoted by the black, filled boxes below each bar; shown are data for a representative donor (rd). The lower part of the figure gives mean (m) and range (r) frequencies for NK subsets expressing different numbers of inhibitory MHC class I receptors, both for the representative donor alone and all 27 donors analyzed. The donors are grouped by KIR haplotype combination. A and B refer to KIR haplotypes defined at the low resolution of gene content¹⁶ ; A1 is defined at the high resolution of allele content. The representative donor has the A1A1 genotype. See Figure S1 for donor KIR and HLA class I genotypes.