Human leukocyte antigen Class II molecules (HLA Class II)

Human leukocyte antigen (HLA) Class II molecules are a group of heterodimeric cell surface glycoproteins that play a central role in the adaptive immune system by presenting exogenous antigenic peptides to CD4+ T helper cells (Wikipedia, 2024). Encoded by the major histocompatibility complex (MHC) region on chromosome 6, the classical molecules include HLA-DR, HLA-DQ, and HLA-DP, which are primarily expressed on professional antigen-presenting cells such as dendritic cells, macrophages, and B cells (MSD Manuals, 2023). Their primary biological function is to orchestrate immune responses against extracellular pathogens and maintain self-tolerance; however, aberrant presentation of self-peptides is a major driver of autoimmune diseases like type 1 diabetes and rheumatoid arthritis (NIH, 2021). In oncology, HLA Class II molecules are often overexpressed in B-cell malignancies, making them targets for monoclonal antibodies like IMMU-114 and 1D09C3, while their downregulation in solid tumors can facilitate immune escape (NCI, 2024). Therapeutic strategies include competitive binding by random copolymers like glatiramer acetate to treat multiple sclerosis and the development of small molecule inhibitors to block specific disease-associated alleles (PubMed, 2022).

Other names

MHC Class IIHLA-IIHLA-DRHLA-DQHLA-DPHLA-DMHLA-DOMajor histocompatibility complex Class II

Drugs targeting HLA Class II molecules primarily act by blocking the peptide-binding cleft to prevent antigen presentation, competitively binding to the molecule to displace autoantigens (e.g., glatiramer acetate), or using monoclonal antibodies to induce apoptosis in HLA-DR-expressing cells (e.g., in B-cell malignancies). Some agents also modulate the transcriptional expression of these molecules via the Class II transactivator (CIITA) or interfere with the catalytic exchange of peptides mediated by HLA-DM.