Diverse NK repertoires are characterized by the degree of receptor coexpression, balance of NKG2A/KIR, and receptor-null cell content. (A) Shown are NK-cell repertoires for 3 KIR A1A1 haplotype donors. Each observed repertoire (■) is compared with a simulated repertoire (□), which is the repertoire expected by the product rule. Donors I and II have Bw4 and C1; donor III has only C1. (B) Comparison of the expression frequencies for the 6 MHC class I receptors expressed independently (single-positive cells) and in combination with KIR. ● represent the frequencies observed for the 58 donors; ○ represent frequencies predicted by the product rule. (C) The inverse correlation between the frequencies of KIR⁺NKG2A⁻ and KIR⁻NKG2A⁺ NK cells in 58 donors with varied KIR and HLA types. The observed frequencies (●) are compared with those expected from the product rule (○). (D) For each donor, the frequency of receptor-null NK cells is plotted against the frequency of cells expressing one or more KIR (▴) and the frequency of cells expressing NKG2A (◇).