T-cell receptor–major histocompatibility complex interaction (TCR–MHC)

The **T-cell receptor–major histocompatibility complex (TCR–MHC) interaction** is the central molecular event of adaptive cellular immunity, enabling T cells to recognize specific antigenic peptides presented by MHC molecules on the surface of antigen-presenting cells or infected/transformed cells[1][2][3][5]. The T-cell receptor (TCR), a membrane-bound heterodimer (usually of α and β chains), interacts with a short peptide-loaded MHC molecule; this recognition requires substantial specificity and is the trigger for T cell activation and downstream immune response[1][2][6][5]. MHC molecules themselves are divided into class I (present to CD8+ T cells) and class II (present to CD4+ T cells), with functionally distinct immunological roles[3][7][2]. The combined TCR–MHC interface defines "MHC restriction" and determines whether a T cell can be activated by a given antigen[3][10]. Disruption or alteration of this interaction can lead to immune deficiency, autoimmunity, malignancy, or transplant rejection[2][3][5][9]. It is not a single molecule but rather an interaction between two distinct immune molecules, both individually valid therapeutic targets (such as engineered TCRs or MHC blockers), but the phrase "TCR/MHC" itself does not refer to one unique protein.

Other names

TCR–MHC complexT cell receptor/major histocompatibility complexTCR/pMHCT cell receptor–MHC interactionTCR–peptide–MHC

Modulate T cell activation by enhancing or blocking TCR–MHC interaction; Redirect T cell specificity (TCR gene therapy, bispecifics); Inhibit antigen presentation (downregulate MHC expression); Immune checkpoint blockade (indirect enhancement of TCR signaling)