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

Major histocompatibility complex class I, A (HLA-A) is a vital cell surface glycoprotein that plays a fundamental role in the adaptive immune system by presenting endogenous peptides to CD8+ cytotoxic T lymphocytes. It consists of a highly polymorphic alpha chain that non-covalently associates with beta-2 microglobulin to form a functional heterodimer capable of binding peptides derived from cytosolic proteins (UniProt: P01892). This mechanism allows the immune system to monitor cellular health, identifying and eliminating cells that present foreign viral or mutated tumor antigens (PubMed: 29739404). In the context of oncology, HLA-A is a cornerstone of precision immunotherapy; many TCR-T cell therapies and cancer vaccines are developed to target specific peptides restricted to common alleles such as HLA-A*02:01 (ClinicalTrials.gov: NCT04044859). However, the high degree of polymorphism in the HLA-A gene poses a significant challenge for universal drug design, and tumors frequently downregulate HLA-A expression to evade immune surveillance (PubMed: 30559445). Therapeutic strategies often require patient screening for specific HLA genotypes to ensure treatment efficacy and minimize the risk of off-target autoimmune reactions.

Other names

Major histocompatibility complex, class I, AMHC class I antigen A*Human leukocyte antigen AHLAA

Drugs targeting HLA-A generally function by utilizing the molecule as a scaffold for antigen presentation. TCR-engineered T-cells and bispecific T-cell engagers (BiTEs) are designed to recognize specific peptides (e.g., MAGE-A4 or gp100) bound specifically within the HLA-A peptide-binding groove, thereby triggering a directed cytotoxic immune response against cells expressing those complexes (NCBI Gene: 3105; UniProt: P01892).