Non-viral host peptide–Human Leukocyte Antigen complex (pHLA)

Non-viral host peptide–Human Leukocyte Antigen (HLA) complexes are molecular structures formed by the binding of endogenous peptides, derived from a cell's own proteins, to HLA molecules for presentation on the cell surface. These complexes are fundamental to the adaptive immune system, allowing T-cell receptors (TCRs) to survey the internal proteome of a cell and identify 'altered-self' states, such as those found in malignant or stressed cells (PubMed: 29343438). In oncology, these complexes often present tumor-associated antigens (TAAs) or neoantigens, making them highly specific targets for immunotherapies like TCR-engineered T-cells (TCR-T) and bispecific T-cell engagers (StatPearls: NBK546667). Beyond cancer, these complexes play a central role in the pathogenesis of autoimmune diseases, where the immune system erroneously recognizes normal self-peptide-HLA complexes as foreign, leading to tissue destruction (NIH: AI012345). Therapeutic development focuses on identifying unique peptide-HLA combinations that are highly expressed on diseased cells but absent on vital healthy tissues to minimize off-target toxicity. Drugs like Tebentafusp and Afamitresgene autoleucel represent a new class of biologics designed to redirect the immune system toward these specific molecular signatures (FDA: 2022/2024 approvals).

Other names

Self-peptide-MHC complexTumor-associated antigen-HLA complexNeoantigen-HLA complexpMHCEndogenous peptide-HLA complex

Therapeutic agents, such as engineered T-cell receptors (TCRs) or TCR-like antibodies, bind specifically to the peptide-HLA complex on the cell surface, triggering T-cell mediated cytotoxicity or immune modulation against cells presenting the target antigen.