Peptide–Major Histocompatibility Complex class II and T-cell receptor complex (pMHCII-TCR complex)

The Peptide–Major Histocompatibility Complex class II (pMHCII) and T-cell receptor (TCR) complex is the central molecular interaction that governs the adaptive immune response to allergens [Larche, 2007]. This complex forms when an antigen-presenting cell (APC) displays a processed allergen peptide within the groove of an MHC class II molecule to a cognate CD4+ T-cell receptor [Worm et al., 2017]. In allergic individuals, this interaction typically leads to the activation of Th2 cells, which drive IgE production and eosinophilic inflammation [Sabatos-Peyton et al., 2010]. Therapeutic targeting of this complex, primarily through peptide-based immunotherapy (PIT), aims to induce immunological tolerance rather than merely suppressing symptoms [Aravax, 2023]. These therapies use short synthetic peptides that bind to MHC II and interact with the TCR but lack the structural complexity to cross-link IgE on mast cells, thereby reducing the risk of anaphylaxis [Larche, 2007]. Successful engagement of the pMHCII-TCR complex in a therapeutic context can lead to T-cell anergy, deletion, or the induction of regulatory T cells (Tregs) that secrete IL-10 and TGF-beta [Sabatos-Peyton et al., 2010]. Monitoring this target often involves the use of fluorescently labeled pMHCII tetramers to track the frequency and phenotype of allergen-specific T cells in patient blood [Kwok et al., 2001].

Other names

pMHCII-TCR interactionAllergen-peptide-MHC-TCR complexAntigen-specific T-cell receptor complexMHC class II-peptide complexImmunological synapse in allergy

Induction of T-cell tolerance (anergy or regulatory T-cell induction) through the presentation of allergen-derived peptides to specific CD4+ T-cell receptors in the absence of pro-inflammatory signals.