Peptide/human leukocyte antigen complex (pHLA complex)

The peptide/human leukocyte antigen (pHLA) complex refers to a structure formed when a processed peptide (derived from endogenous or exogenous proteins) binds within the peptide-binding groove of a human leukocyte antigen (HLA) molecule—also known as a major histocompatibility complex (MHC) molecule—on the surface of nucleated cells[1][2][4][6][9]. This complex is essential for the recognition of antigens by T cell receptors (TCRs), facilitating immune selection and immune surveillance[4][6][9]. HLA molecules are highly polymorphic, and the spectrum of peptides they present determines the repertoire of immune responses, individualized for each person[1][5][9]. The pHLA complex is central to the control of infection, tumor surveillance, autoimmunity, and holds immense relevance in contexts such as transplantation and cancer immunotherapy[2][4][10]. Disruption or alteration of peptide/HLA presentation can lead to immune evasion by tumors or pathogens, and inappropriate targeting can trigger autoimmunity or transplant rejection[4][5]. Peptide/HLA complexes are thus principal therapeutic targets, especially for vaccine design, TCR-mimetic biologics, and cellular immune therapies[2][4][9].

Other names

Peptide-major histocompatibility complex (MHC) complexPeptide-HLA complexpMHC complex

Drugs or biologics that target or utilize the peptide-HLA complex generally act by blocking or enhancing recognition by T cell receptors (TCRs) Some engineered molecules (e.g., TCR mimetics or bispecifics) bind specific peptide-HLA complexes to mediate targeted cytotoxicity Cancer immunotherapies often exploit presentation of tumor-specific peptides on HLA for T cell targeting