T cell receptor–peptide–major histocompatibility complex complex (TCR–peptide–MHC complex)

The T cell receptor–peptide–major histocompatibility complex complex (TCR–peptide–MHC complex) is a trimeric protein assembly that forms the molecular basis for antigen recognition by T cells, a central event in adaptive immunity. The T cell receptor (TCR) on the surface of T lymphocytes specifically recognizes antigenic peptides that are bound and presented by major histocompatibility complex (MHC) molecules on the surfaces of antigen-presenting cells. This recognition event triggers intracellular signaling cascades through the associated CD3 complex, leading to T cell activation, expansion, and execution of immune functions such as cytotoxicity or cytokine production[1][2][3][5][6]. The TCR–peptide–MHC interaction is highly specific, with the TCR engaging both the presented peptide and the MHC molecule; this specificity enables discrimination between self and non-self peptides and underlies T cell-mediated immune surveillance against infected or malignant cells. The diversity of TCRs, the polymorphism of MHC molecules, and the vast repertoire of possible peptides provide adaptability but also pose challenges for predicting TCR specificity and for therapeutic targeting. Therapies targeting this molecular assembly include engineered TCR-T cells for cancer immunotherapy, peptide vaccines, and monoclonal antibodies that mimic TCR specificity[5][3][7]. Cross-reactivity, off-target effects, and immune-related adverse events are notable safety concerns in the therapeutic modulation of this complex[1][5].

Other names

TCR–pMHC complexT cell receptor–peptide–MHC complexTCR–MHC complexTCR–antigen–MHC complex

Modulate T cell activation by enhancing or inhibiting TCR recognition of peptide–MHC; Redirect T cell specificity using engineered TCRs; Blockade or mimicry of peptide–MHC epitopes.