Endogenous peptide–Major Histocompatibility Complex class II complex (pMHCII)

The endogenous peptide–Major Histocompatibility Complex class II (pMHCII) complex on dendritic cells is a critical molecular assembly that presents self-derived peptides to CD4+ T-cells to maintain immunological self-tolerance (Roche & Furuta, 2015, Nature Reviews Immunology). Dendritic cells process internal proteins and display these fragments within the groove of MHC II molecules, such as HLA-DR, HLA-DQ, and HLA-DP, which are then recognized by the T-cell receptor (TCR) (Unanue et al., 2016, Annual Review of Immunology). In autoimmune conditions, the aberrant presentation of specific endogenous peptides or the failure of the immune system to remain tolerant to these complexes leads to the activation of autoreactive T-cells and subsequent tissue damage (Santamaria, 2020, Cold Spring Harbor Perspectives in Medicine). Therapeutic interventions targeting this complex include antigen-specific immunotherapies like glatiramer acetate, which competes for MHC II binding, and novel pMHC-coated nanoparticles designed to expand regulatory T-cell populations (Clemente-Casares et al., 2016, Nature). These approaches aim to reprogram the immune system toward tolerance without the side effects of global immunosuppression. However, the high degree of HLA polymorphism in the human population necessitates a personalized approach, as the specific peptide-MHC interaction is highly dependent on an individual's genetic background. Monitoring these complexes and the T-cells that recognize them is essential for evaluating the efficacy of tolerogenic vaccines and cell-based therapies.

Other names

Self-peptide–MHC II complexpMHCII complexMHC class II–antigen complexHLA-peptide complexEndogenous pMHCII

Induction of antigen-specific immune tolerance through the expansion of regulatory T-cells, induction of T-cell anergy, or competition for MHC class II binding sites.