Major histocompatibility complex–peptide–T cell receptor interface

The **major histocompatibility complex–peptide–T cell receptor (MHC–peptide–TCR) interface** is a molecular complex formed when a peptide antigen is presented by an MHC molecule on the surface of an antigen-presenting cell and specifically recognized by the T cell receptor (TCR) on a T lymphocyte[1][2][3][5][6]. This tripartite interface is central to adaptive immunity, governing the specificity of T cell–mediated recognition of self versus non-self. The MHC molecule presents a bound peptide within its groove, and the TCR docks diagonally across the peptide-MHC platform, with its complementarity-determining regions (CDRs) making fine contacts both with the peptide and the MHC molecule[3][4][5]. Recognition of this complex leads to intracellular signaling via the associated CD3 complex, contributing to T cell selection, activation, and effector functions[2][6]. Therapeutically, this interface is targeted by engineered TCRs, TCR-mimic antibodies, bispecific modalities, and peptide-based vaccines, particularly in cancer and infectious disease[5][6]. Targeting is challenging due to the extensive polymorphism of MHC molecules, the vast diversity in TCR specificity, and the risk of cross-reactivity with self-peptides, leading to potential safety concerns like autoimmunity and cytokine release syndrome[5]. The interface serves not only as a functional signaling unit but also as a focal point for immunotherapy development, including precision identification and monitoring of T cell responses using pMHC tetramers and neoantigen mapping[6].

Other names

MHC–peptide–TCR complexpMHC–TCR interfaceT cell receptor–peptide–MHC interaction

Specific engagement of TCRs to MHC-presented epitopes leads to activation (or inhibition) of T cells, which can be leveraged for immune-targeting of disease-specific antigens in cancer and infection Modulation of the interface to block or stimulate immune synapse formation (e.g., TCR-mimic antibodies, bispecifics, engineered cell therapies such as TCR-T cells)