Tumor cell major histocompatibility complex–peptide complex

The **tumor cell major histocompatibility complex–peptide complex** refers to the structure formed when a major histocompatibility complex (MHC) molecule on the surface of a tumor cell binds a peptide, usually derived from endogenous or mutated tumor proteins. These complexes are recognized by T-cell receptors on cytotoxic (CD8+) T cells (for MHC class I) or helper (CD4+) T cells (for MHC class II), triggering immune responses against the tumor. Downregulation or absence of these complexes is a common tumor immune evasion mechanism, linked to poor prognosis and reduced response to immune checkpoint blockade therapies[1][2][3][4][7]. Therapeutic strategies and drugs that restore or increase MHC-peptide presentation on tumor cells are being developed to enhance tumor immunogenicity and response to immunotherapy[1][3][4]. Both MHC-I and MHC-II complexes on tumors are emerging as important targets and biomarkers in cancer immunology[1][4][7].

Other names

MHC–peptide complex (on tumor cells)tumor MHC–peptide complextumor antigen–MHC complexpMHC (peptide–MHC)tumor cell MHC class I–peptidetumor cell MHC class II–peptide

Upregulation of MHC expression (e.g., IFN or retinoids) enhances antigen presentation to cytotoxic T cells Restoration or increased presentation facilitates recognition by T-cell receptors, especially CD8+ (MHC-I) and CD4+ (MHC-II)