Tumor antigen presented on major histocompatibility complex class I

Tumor antigens presented on major histocompatibility complex (MHC) class I molecules comprise peptides derived from intracellular (endogenous) proteins—including mutated or aberrantly expressed proteins in cancer cells—that are processed by the proteasome, loaded onto MHC class I via the antigen-processing machinery (TAP1, TAP2, other chaperones), and displayed on the cell surface. These peptide-MHC complexes are recognized by cytotoxic T lymphocytes (CD8+ T cells), which can eliminate malignant cells. Many cancers evade immune surveillance by disrupting this pathway: mechanisms include loss or mutation of MHC I components (e.g., β2-microglobulin), defects in the antigen-processing machinery, and reduced surface expression of MHC I. Restoration and enhancement of tumor antigen presentation are central to cancer immunotherapies, such as checkpoint blockade, adoptive T-cell transfer, and peptide vaccines[1][2][4][3]. This concept refers not to a single protein target but to the molecular presentation event/platform enabling immune recognition and attack.

Other names

Tumor antigen-MHC complexPeptide-MHC complexTumor antigen presented by MHC IMHC class I-presented tumor antigen

Enhancement of T-cell recognition by restoring or boosting tumor antigen presentation Blocking immune evasion by reactivating immune recognition (e.g., checkpoint inhibitors) Delivery of synthetic peptides to increase antigen presentation