Peptide-Major Histocompatibility Complex class II (pMHCII)

Peptide-Major Histocompatibility Complex class II (pMHCII) is a molecular complex consisting of an MHC class II heterodimer (comprising alpha and beta chains) and a bound peptide fragment, typically 12-25 amino acids in length [7, 16]. Primarily expressed on the surface of professional antigen-presenting cells (APCs) such as dendritic cells, B cells, and macrophages, pMHCII complexes are essential for the adaptive immune system [7, 13]. Their primary biological function is to present exogenous antigens to CD4+ T helper cells, which then coordinate the adaptive immune response, including B cell activation and the recruitment of other immune effectors [9, 17]. In autoimmune diseases, pMHCII complexes presenting self-peptides trigger the activation of autoreactive T cells, leading to chronic inflammation and tissue destruction [1, 21]. Conversely, in oncology, they can present tumor-associated antigens or neoantigens, serving as critical targets for anti-tumor immunity [8, 23]. Therapeutic strategies targeting pMHCII include the development of TCR-like antibodies to block pathogenic interactions or eliminate specific APCs, and peptide-based vaccines or copolymers designed to induce immune tolerance or enhance anti-tumor responses [4, 30].

Other names

pMHC-IIMHC II-peptide complexHLA-peptide complexAntigen-MHC class II complexPeptide-MHC II complexPeptide-Major Histocompatibility Complex class II complex

Competitive inhibition of peptide binding to MHC II molecules, induction of antigen-specific regulatory T cells (Tregs), and direct blocking of the T-cell receptor (TCR) interaction with the peptide-MHC complex [1, 21, 29, 30].