Peptide-Major Histocompatibility Complex-T-cell receptor complex (pMHC-TCR complex)

The Peptide-Major Histocompatibility Complex-T-cell receptor (pMHC-TCR) complex is the fundamental molecular assembly that mediates antigen recognition and T-cell activation in the adaptive immune system. It consists of a short peptide fragment—derived from intracellular proteins such as tumor-associated antigens (TAAs) or mutation-generated neoantigens—bound within the groove of a Major Histocompatibility Complex (MHC) molecule and recognized by a specific T-cell receptor (TCR). This interaction allows the immune system to monitor the internal state of cells and identify malignant transformations that do not necessarily involve cell-surface proteins. In oncology, this complex is the primary target for advanced immunotherapies, including TCR-engineered T cells (TCR-T), TCR-bispecific engagers (ImmTACs), and cancer vaccines, which aim to redirect the immune system to eliminate tumor cells with high specificity. However, the therapeutic application is complicated by the risk of off-target cross-reactivity with similar self-peptides in healthy tissues, which can lead to severe toxicities, and the potential for tumor escape through the downregulation of MHC molecules.

Other names

pMHC-TCR complexTCR-pMHC complexAntigen-MHC-TCR complexTrimolecular complexPeptide-HLA-TCR complexpMHC-TCR synapseTumor antigen-MHC-TCR complex

Antigen-specific T-cell activation and redirected cytotoxicity against cells presenting cognate peptide-MHC complexes.