Antigenic peptide–major histocompatibility complex (pMHC)

The antigenic peptide–major histocompatibility complex (antigenic peptide–MHC or pMHC) is a molecular complex formed by a short peptide antigen bound within the cleft of a major histocompatibility complex (MHC) molecule on the surface of antigen-presenting cells[1][2][3][4][5]. The pMHC complex is responsible for displaying intracellular or extracellularly derived peptides to T cell receptors (TCRs), thereby enabling the immune system to detect infected, cancerous, or otherwise abnormal cells[1][2]. There are two primary classes of pMHC: class I (found on all nucleated cells, presents peptides to CD8+ cytotoxic T lymphocytes) and class II (found primarily on antigen-presenting cells, presents peptides to CD4+ helper T lymphocytes)[1][4]. The diversity of pMHC complexes allows recognition of a vast array of peptide antigens, critical for pathogen clearance and self–nonself discrimination. Aberrant pMHC presentation or recognition is implicated in multiple diseases, including autoimmunity, infection, transplantation rejection, and cancer[1][4]. The pMHC is a major focus of immunotherapeutic drug development, including T cell–engaging biologics, vaccines, and engineered T cell therapies.

Other names

peptide–MHC complexpMHC complexMHC–peptide complexantigen–MHC complex

Modulation of antigen presentation to T cells, determining activation or inhibition of immune response[1][2][4] and direct targeting or mimicking of pMHC complexes to elicit or block T cell responses.