Nature of polymorphism in HLA-A, -B, and -C molecules

Abstract

Diversity in 39 HLA-A, -B, and -C molecules is derived from 20 amino acid positions of high variability and 71 positions of low variability. Variation in the structurally homologous α1 and α2 domains is distinct and may correlate with partial segregation of peptide and T-cell receptor binding functions. Comparison of 15 HLA-A, with 20 HLA-B molecules reveals considerable locus-specific character, due primarily to differences at polymorphic residues. The results indicate that genetic exchange between alleles of the same locus has been a more important mechanism in the generation of HLA-A, -B, and -C diversity than genetic exchange events between alleles of different loci.