KIR expression on CD8 T cells is independent of self-HLA class I ligands. (A) Staining for KIR2DL1, KIR2DL3, and KIR3DL1 on CD45RA⁺CD57⁺ CD8 T cells in 3 representative individuals with known HLA genotypes where C1 is the ligand of KIR2DL3, C2 is the ligand of KIR2DL1, and Bw4 is the ligand of KIR3DL1. Numbers in the figures represent frequency of indicated KIR out of total CD45RA⁺CD57⁺ CD8 T cells. (B-C) Observed frequencies of CD45RA⁺CD57⁺ CD8 T cells (B) and NK cells (C) expressing self-and nonself-KIRs compared with theoretical values of random KIR expression analyzed for 24 individuals with 2 KIR ligands present (n.s. indicates not significant; Wilcoxon matched pairs test; mean).