Peptide–major histocompatibility complex on autologous tumor cell (pMHC (context-specific; "pMHC" is common))

The peptide–major histocompatibility complex (peptide–MHC, or pMHC) on autologous tumor cells is a molecular complex consisting of a short peptide, typically derived from endogenous (often tumor-specific) proteins, bound within the cleft of a class I or II MHC molecule on the surface of the same patient’s tumor cell. T cell receptors scan and recognize these pMHC complexes, initiating immune recognition if the peptide is foreign or aberrant. The display of immunogenic peptides in the pMHC context is critical for antitumor T cell responses and underlies the mechanism of many immunotherapy approaches, including personalized cancer vaccines, TCR-engineered T cells, and bispecific antibodies. MHC class I typically presents peptide to CD8+ T cells (cytotoxic), while class II presents to CD4+ T cells (helper), and altered expression or loss of these complexes on tumor cells enables immune evasion[1][4][2].

Other names

Peptide–MHC complexPeptide–HLA complex (human-specific)Tumor-associated peptide–MHC complexpMHC complex

Recognition by T cell receptor (TCR) on cytotoxic or helper T cells, leading to immune activation, tumor cell lysis, or modulation of immune response[4]. Artificial targeting by antibodies, fusion proteins, or TCR mimetics designed to bind to specific peptide–MHC complexes, redirecting immune effector functions[2]