Cutting edge: Allele-specific and peptide-dependent interactions between KIR3DL1 and HLA-A and HLA-B

Although it is clear that KIR3DL1 recognizes Bw4⁺ HLA-B, the role of Bw4⁺ HLA-A allotypes as KIR3DL1 ligands is controversial. We therefore examined the binding of tetrameric HLA-A and -B complexes, including HLA*2402, a common Bw4⁺ HLA-A allotype, to KIR3DL1*001, *005, *007, and *1502 allotypes. Only Bw4⁺ tetramers bound KIR3DL1. Three of four HLA-A*2402 tetramers bound one or more KIR3DL1 allotypes and all four KIR3DL1 allotypes bound to one or more HLA-A*2402 tetramers, but with different binding specificities. Only KIR3DL1*005 bound both HLA-A*2402 and HLA-B*5703 tetramers. HLA-A*2402-expressing target cells were resistant to lysis by NK cells expressing KIR3DL1*001 or *005. This study shows that HLAA*2402 is a ligand for KIR3DL1 and demonstrates how the binding of KIR3DL1 to Bw4⁺ ligands depends upon the bound peptide as well as HLA and KIR3DL1 polymorphism.