HLA class I histocompatibility antigen, A alpha chain (HLA-A)

HLA class I histocompatibility antigen, A alpha chain (commonly abbreviated HLA-A) is a membrane-bound glycoprotein encoded by the HLA-A gene, forming part of the major histocompatibility complex class I (MHC I) family[3][1][5]. It consists of a polymorphic α chain (heavy chain) that associates with β2-microglobulin. HLA-A binds intracellularly processed peptides—typically 8–13 amino acids—derived from endogenous proteins (e.g., viral, tumor, or self-proteins), presenting them on the cell surface to CD8+ T cells, which can then recognize and eliminate abnormal or infected cells[1][3][5]. The molecule contains distinct peptide-binding pockets, and polymorphism in the α chain determines peptide repertoire and immune recognition specificity[1][3]. Variation among alleles (e.g., A*24) is clinically relevant for transplantation, susceptibility/resistance to infectious and autoimmune diseases, and response to immunotherapies. It is central to immune surveillance, transplantation medicine, and cancer immunology.

Other names

HLA-AMajor histocompatibility complex, class I, AHuman leukocyte antigen AMHC class I antigen A

Drugs that depend on or modulate HLA class I antigen presentation function by:\n- Enhancing or inhibiting antigen presentation to T-cells\n- Modulating immune recognition (checkpoint inhibitors release immune suppression, allowing T cells to recognize peptide-MHC complexes on cancer cells)\n- Altering peptide loading for immune response modulation