Peptide-Human Leukocyte Antigen A1 complex (pHLA-A1)

The peptide-HLA-A1 complex is a molecular assembly consisting of a specific antigenic peptide non-covalently bound to the groove of the Human Leukocyte Antigen A1 (HLA-A1) protein, a Major Histocompatibility Complex (MHC) class I molecule (UniProt: P04439). This complex is expressed on the surface of nucleated cells and serves as the primary signal for recognition by CD8+ T cells via their T-cell receptors (TCRs) (PubMed: 23908460). In oncology, HLA-A1 is frequently used to present tumor-associated antigens, such as those from the MAGE family, making it a critical target for adoptive cell therapies and cancer vaccines (PubMed: 21300902). The specificity of the interaction depends on both the HLA allele and the sequence of the bound peptide, which determines the immune system's ability to distinguish between self and non-self. Therapeutic strategies often involve engineering TCRs or antibodies to recognize these specific complexes to selectively eliminate malignant or infected cells. However, a major challenge in targeting these complexes is the risk of cross-reactivity with similar peptides presented on healthy tissues, which can lead to severe adverse effects. For example, clinical trials targeting MAGE-A3 presented by HLA-A1 revealed fatal cardiotoxicity due to unexpected recognition of a similar peptide in the protein Titin (Linette et al., Blood, 2013). Despite these challenges, the peptide-HLA-A1 complex remains a high-value target for precision immunotherapy due to its ability to present intracellular proteins that are otherwise inaccessible to traditional antibody therapies.

Other names

HLA-A*01-peptide complexMHC class I A1-peptide complexHLA-A1-restricted antigenPeptide-HLA-A*01 complex

The complex acts as a ligand for the T-cell receptor (TCR) on CD8+ cytotoxic T lymphocytes. Therapeutic agents, such as TCR-engineered T cells or TCR-mimetic antibodies, bind specifically to the peptide-HLA interface to trigger an immune response against cells displaying the target antigen.