Human leukocyte antigen class I heavy chain A-2 or A-3 (HLA-A2 (or HLA-A3))

Human leukocyte antigen class I molecules (such as HLA-A2 or HLA-A3) are cell surface glycoproteins encoded by the HLA-A gene locus, part of the major histocompatibility complex (MHC) class I system. These proteins are composed of a polymorphic heavy chain (which specifies A2, A3, etc.) non-covalently associated with beta-2 microglobulin and a short peptide derived from intracellular proteins. The peptide–HLA complex is transported to the cell surface, where it presents peptide antigens to CD8+ cytotoxic T lymphocytes. This mechanism is central to antiviral immunity, anti-tumor surveillance, and immune self/nonself discrimination. HLA-A2 and HLA-A3 are common polymorphic variants (alleles) within the population, highly relevant for immune responses, disease susceptibility, and organ transplantation[1][2][3][4]. Note: HLA-A2 and HLA-A3 are two specific alleles of the HLA-A gene encoding MHC class I molecules; both are correctly described as "HLA-A2 or HLA-A3 MHC class I heavy chain" and are legitimate therapeutic/research targets due to their roles in antigen presentation and immune recognition[1][3][4].

Other names

HLA-A2HLA-A3HLA-A*02HLA-A*03HLA-AMHC class I moleculeMHC-IMajor histocompatibility complex class I

Presentation of intracellular peptides to CD8+ T-cells Activation of cytotoxic immune response against infected or malignant cells Indirect modulation by drugs that enhance antigen presentation or T-cell responsiveness