Major histocompatibility complex class I antigen HLA-A (HLA-A)

Major histocompatibility complex class I antigen HLA-A (HLA-A) is a transmembrane glycoprotein expressed on almost all nucleated human cells and platelets, comprised of a polymorphic heavy chain (encoded by the HLA-A gene) and the invariant beta-2 microglobulin light chain[1][2][3]. HLA-A molecules present peptides (usually 8–10 amino acids) derived from intracellular (endogenous) proteins to cytotoxic CD8+ T cells, enabling discrimination between self and non-self and the elimination of infected or malignant cells[1][2]. The high diversity of HLA-A alleles influences susceptibility to infections, autoimmune diseases, and transplant compatibility; HLA-A typing is critical in organ and bone marrow transplantation and a key determinant of individual immune responses to pathogens and cancers[2]. Loss, mutation, or downregulation of HLA-A is a known mechanism by which tumors and viruses evade immune detection. While HLA-A is not directly targeted by small-molecule drugs or antibodies, its role in antigen presentation makes it fundamental for immunotherapies that depend on T cell–mediated recognition[2].

Other names

HLA-AHLA class I histocompatibility antigen, A alpha chainHuman leukocyte antigen AHLA class I histocompatibility antigen, A-1 alpha chainMHC class I antigen HLA-A heavy chainleukocyte antigen class I-A

Drugs and therapies targeting HLA-A exploit immune recognition, such as peptide-based cancer vaccines, T cell receptor (TCR)–engineered cell therapies, and immune checkpoint inhibitors that rely on HLA-A presentation to trigger cytotoxic T cell responses