HLAB5701restricted

HLAB5701restricted refers to immune responses that are restricted by the HLA-B*57:01 allele, a class I major histocompatibility complex molecule. In immunology, a T cell response is described as restricted to a specific HLA allele when recognition of an antigen peptide requires presentation by that particular MHC molecule. HLA-B*57:01-restricted responses are central to certain antiviral and drug-related immune reactions.

The most clinically important association is with abacavir hypersensitivity reaction (ABC HSR) in people who carry HLA-B*57:01. The hypersensitivity is believed to arise because abacavir binds within the peptide-binding groove of HLA-B*57:01, altering the repertoire of self-peptides and triggering a cytotoxic T-cell response in susceptible individuals. This reaction is strongly associated with HLA-B*57:01 and is typically observed within the first six weeks of therapy. To prevent HSR, guidelines recommend genetic testing for HLA-B*57:01 before initiating abacavir, and if positive, abacavir is avoided.

Prevalence varies by ethnicity; the allele occurs at different frequencies in populations. The HLA-B*57:01 restriction concept has guided pharmacogenomics, leading to safer prescribing and the development of screening programs. It also illustrates how MHC-restricted T cell responses can underlie drug hypersensitivity, distinct from infectious antigen recognition.