HLA class I histocompatibility antigen alpha chain A*02 (HLA-A*02)

HLA class I histocompatibility antigen alpha chain A*02 (commonly known as **HLA-A*02**) is a member of the major histocompatibility complex (MHC) class I family. It consists of a polymorphic heavy α-chain encoded by the **HLA-A** gene at locus 6p21.3 paired with β2-microglobulin as its light chain. The primary function of this molecule is to present endogenous peptides—typically derived from viral proteins or tumor antigens—on the surface of nearly all nucleated cells for surveillance by CD8+ cytotoxic T lymphocytes. Recognition of these peptide-MHC complexes triggers targeted immune responses against infected or transformed cells. The **A*02** allele group is one of the most common globally and exhibits extensive polymorphism; over 450 protein variants have been described within this group alone. The serotype "A2" refers specifically to antibody recognition patterns associated with these alleles. Clinically, **HLA-A*02** plays critical roles in transplantation compatibility testing, infectious disease susceptibility/resistance profiling, cancer immunotherapy design (as many tumor antigens are presented preferentially by certain alleles), and reproductive immunology where certain alleles may be linked with increased risk for spontaneous abortion due to heightened maternal immune response against fetal tissues expressing paternal HLAs.

Other names

HLA-A2HLA-A*2Human leukocyte antigen A*02

Drugs or biologics that utilize this target act by presenting specific peptides on the surface of cells via the MHC class I pathway. This enables recognition and killing of infected or malignant cells by CD8+ cytotoxic T lymphocytes. Peptide-based cancer vaccines and engineered TCR-T cell therapies are designed to exploit this mechanism in an HLA-A*02-restricted manner.