Peptide-major histocompatibility complex class II–T-cell receptor interface

The peptide-major histocompatibility complex class II–T-cell receptor interface refers to the molecular surface formed when a T-cell receptor (TCR) on a CD4+ T cell specifically engages a peptide bound within the antigen-binding groove of a major histocompatibility complex (MHC) class II molecule displayed on an antigen-presenting cell[2][4][5][6]. This interface is central to adaptive immunity, as it enables T cells to sense foreign or self peptides and trigger appropriate immune responses or tolerance[1][4][5]. The structure is characterized by the variable complementarity-determining region (CDR) loops of the TCR contacting both the presented peptide (often residues P-1 to P8, anchored in the MHC groove) and the MHC α- and β-helices, with the TCR typically oriented diagonally across the peptide–MHC surface[2][4][6][7]. Interfacial variability underlies the immense diversity of T cell antigen recognition and is a major determinant in immune recognition, autoimmunity, infection, and response to immunotherapy. The interaction is modifiable by superantigens and can be exploited or disrupted in therapy, but broad targeting carries risks of immune dysregulation and off-target effects[2][4][5].

Other names

Peptide-MHC class II/TCR interfacepMHCII–TCR interfaceTCR–peptide–MHC class II interfaceTCR–pMHCII interaction

Interference with antigen recognition (blocking or altering peptide presentation or TCR recognition); Immune modulation (tolerogenic peptides, immune checkpoint targeting); Superantigen cross-linking (non-specific polyclonal T cell activation causing immune pathology)