Human leukocyte antigen B*57:01 (HLA-B*57:01)

Human leukocyte antigen B*57:01 (HLA-B*57:01) is a specific allelic variant of the HLA-B gene, which encodes a major histocompatibility complex (MHC) class I molecule. These molecules are expressed on the surface of nearly all nucleated cells where they present intracellularly derived peptides (including viral or pathogen-derived fragments) to CD8+ cytotoxic T cells, enabling immune surveillance and self/non-self discrimination. HLA-B*57:01 differs from other HLA-B variants by a small number of amino acid changes that specifically impact peptide binding characteristics. This subtype is most clinically notable because its presence strongly predicts risk of severe, sometimes life-threatening hypersensitivity reactions in individuals treated with the HIV drug abacavir. Abacavir interacts directly with the peptide-binding groove of HLA-B*57:01, changing the set of presented peptides and triggering inappropriate immune responses. For this reason, HLA-B*57:01 genotyping is recommended or required before initiating abacavir therapy, making it a validated pharmacogenetic biomarker for drug safety. Beyond pharmacogenomics, HLA-B*57:01 may play a broader role in susceptibility to certain infections and autoimmune phenomena, as with many HLA class I alleles, due to its central function in regulating antigen-specific T cell immunity.

Other names

HLA-B*5701B*57:01HLA-B5701

Drug-induced alteration of peptide binding repertoire (notably, abacavir binds within the peptide-binding groove of HLA-B*57:01, altering the repertoire of self-peptides presented to T cells, and may elicit a polyclonal T cell immune reaction)