Major histocompatibility complex peptide–T cell receptor complex

The **major histocompatibility complex peptide–T cell receptor complex** is a multi-protein structure essential for adaptive immunity, formed when a T cell receptor (TCR) on the surface of a T cell engages a specific peptide presented by a major histocompatibility complex (MHC) molecule on an antigen-presenting cell[1][2][3][4][5][7]. MHC molecules, known as human leukocyte antigens (HLA) in humans, bind short peptides derived from self or non-self proteins and present them on the cell surface for surveillance by TCRs. The specificity of this recognition defines antigen specificity and self/nonself discrimination, providing immune defense against pathogens, malignancy, and aberrant cells but also underlies autoimmunity and transplant rejection[1][3][4]. This complex is highly polymorphic due to MHC variability and is a key focus for therapies aiming to harness or modulate T cell responses, including engineered TCRs, vaccines, and biologics. Structural studies reveal that TCRs contact both the MHC molecule and the bound peptide, with the CDR1 and CDR2 loops generally engaging the MHC and the CDR3 loop engaging the peptide, establishing specificity for antigen recognition and initiating T cell activation[3][5][7]. Therapies targeting this complex or its components must consider risks of cross-reactivity and immune-related side effects.

Other names

MHC–peptide:TCR complexpeptide–MHC:TCR complexpMHC:TCR complexTCR–pMHC complexpeptide–MHC–T cell receptor complex

Blockade or modulation of T cell activation by interfering with TCR–pMHC recognition; Redirection of T cell specificity (engineered TCRs, bispecifics); Immune checkpoint modulation (e.g., anti-PD-1/PD-L1), indirectly affect signaling downstream of the TCR–pMHC interaction