Human leukocyte antigen A (HLA-A) peptide-binding groove (HLA-A)

The Human leukocyte antigen A (HLA-A) peptide-binding groove is a specialized structural domain within the MHC class I molecule responsible for presenting endogenous antigens to the immune system. Formed by the alpha-1 and alpha-2 helices of the HLA-A heavy chain, this groove binds short peptides (typically 8-11 amino acids) derived from the proteasomal degradation of intracellular proteins [1, 2]. The specific alleles HLA-A2 (notably A*02:01) and HLA-A3 (notably A*03:01) are among the most prevalent in human populations and are characterized by distinct anchor residue preferences that determine which peptides can be presented [2, 5]. This presentation is essential for CD8+ T-cell surveillance, as the T-cell receptor (TCR) recognizes the specific peptide-HLA complex to trigger an immune response against viral infections or cancerous mutations [5]. In therapeutic contexts, the HLA-A peptide-binding groove is the focal point for MHC-restricted therapies, such as TCR-engineered T cells (TCR-T) and immune-mobilizing monoclonal TCRs against cancer (ImmTACs) [3, 4]. For example, drugs like tebentafusp target the gp100 peptide specifically when presented in the HLA-A*02:01 groove [3]. The primary challenge in targeting this site is the high degree of polymorphism across the human population, requiring patient-specific HLA typing as a biomarker for treatment eligibility [4]. Additionally, there is a significant risk of off-target toxicity if the therapeutic agent cross-reacts with similar self peptides presented on healthy tissues [5].

Other names

MHC class I antigen AHLA-A*02HLA-A*03HLA-A2HLA-A3HLA class I histocompatibility antigen A alpha chain

The HLA-A groove presents intracellularly derived peptides to CD8+ T cells via the T-cell receptor (TCR), enabling the immune system to recognize and destroy cells expressing foreign or mutated antigens [1, 5].