T-cell receptor–major histocompatibility complex (MHC) complex (TCR–MHC complex (or TCR–HLA complex in human context))

The **T-cell receptor–major histocompatibility complex (MHC) complex** (commonly abbreviated as TCR–MHC or TCR–HLA in humans) is a macromolecular assembly essential for adaptive immunity. The complex forms when a T-cell receptor (TCR), a heterodimeric cell-surface receptor on T lymphocytes, specifically binds to a peptide antigen presented by a major histocompatibility complex (MHC) molecule (called HLA in humans) on antigen-presenting cells[2][3][4][6][7][10]. This recognition event is the primary mechanism by which T cells detect pathogen-derived peptides or abnormal self-proteins[2][4][7]. The TCR-MHC complex consists structurally of an αβ (or less frequently, γδ) TCR engaging a peptide-loaded MHC class I or II molecule, each with their own highly variable antigen-presenting domains[1][2][6][10]. This interaction is stabilized by coreceptors (CD4 or CD8) and associated with the CD3 complex, which transduces activation signals into the T cell[2][4][7][9]. Dysregulation or aberrant recognition by this complex underlies multiple disease processes, including infection, cancer, autoimmunity, and transplant rejection[9][10]. Pharmacologic targeting is challenging due to specificity requirements and safety risks (autoimmunity, cytokine release), but forms the basis for some advanced immunotherapies[9].

Other names

TCR–MHC complexT-cell receptor–peptide–MHC complexTCR–HLA complexTCR–pMHC complexT-cell receptor–major histocompatibility complex complexTCR–antigen–MHC complex

Blockade or modulation of TCR-pMHC interaction (by engineered TCRs, TCR mimetics) - Enhancement of T cell activation (by blocking inhibitory checkpoint pathways) - Targeted lysis of HLA-presenting cells by redirected TCR or BiTE therapies - Immunomodulation via altered antigen presentation