Major histocompatibility complex class II (MHC II)

Major histocompatibility complex class II (MHC II) molecules are a family of cell surface glycoproteins primarily expressed on professional antigen-presenting cells (APCs), including dendritic cells, macrophages, and B cells (StatPearls, 2023). Their primary biological function is to present processed exogenous peptides to CD4+ T-helper cells, thereby initiating and coordinating the adaptive immune response (UniProt, 2024). This interaction is fundamental for the development of humoral immunity and the activation of macrophages. In humans, these molecules are encoded by the Human Leukocyte Antigen (HLA) system, specifically the HLA-DR, HLA-DQ, and HLA-DP loci (PubMed, 2022). MHC II molecules play a critical role in the pathogenesis of numerous autoimmune diseases, such as rheumatoid arthritis and type 1 diabetes, where specific HLA alleles are associated with the presentation of self-antigens (NIH, 2023). In oncology, MHC II expression on tumor cells can influence the immune microenvironment and is the ligand for the immune checkpoint LAG-3, making it a target for checkpoint inhibitors like relatlimab (Nature Reviews Drug Discovery, 2022). Therapeutic interventions targeting MHC II include glatiramer acetate, which competes for peptide binding in multiple sclerosis, and various biologics designed to modulate T-cell activation or deplete APCs.

Other names

HLA class IIHuman leukocyte antigen class IIMHC-IIMHC2HLA-DRHLA-DQHLA-DP

Competitive inhibition of peptide binding within the MHC II groove, modulation of the MHC II-LAG-3 inhibitory checkpoint, and interference with antigen presentation to CD4+ T cells.