Major histocompatibility complex–peptide–T-cell receptor complex (MHC-p-TCR) (MHC-p-TCR)

The Major histocompatibility complex–peptide–T-cell receptor (MHC–peptide–TCR) complex is the fundamental structural unit of the adaptive immune system, responsible for the recognition of specific antigens by T-cells (Frontiers in Immunology, 2021). This tripartite axis consists of a peptide fragment presented by an MHC molecule on the surface of an antigen-presenting or target cell, which is then recognized by a specific TCR on a T-lymphocyte (Nature Reviews Immunology, 2022). The interaction triggers a signaling cascade through the CD3 complex, leading to T-cell activation, proliferation, and effector functions such as the targeted lysis of infected or malignant cells. In oncology, this axis is a primary target for TCR-engineered T-cell therapies (TCR-T) and soluble TCR-bispecifics (ImmTACs), which redirect T-cells to recognize tumor-specific peptides that are otherwise invisible to conventional antibodies (Journal of Hematology & Oncology, 2023). Conversely, in the context of autoimmune diseases and transplantation, therapeutic strategies aim to inhibit or modulate this interaction to prevent the destruction of healthy tissues or the rejection of allografts. The high specificity and affinity of this interaction are critical for therapeutic efficacy, though cross-reactivity with self-peptides remains a significant safety challenge in drug development (Science Translational Medicine, 2013).

Other names

TCR-pMHC complexpMHC-TCR axisAntigen-MHC-TCR complexImmunological synapse (core)

The axis is targeted through the engineering of T-cells with high-affinity TCRs (TCR-T), the use of bispecific T-cell engagers that bind both the pMHC and the TCR-CD3 complex, or the administration of antibodies that modulate the signaling threshold of the TCR complex.