HLA class II histocompatibility antigen, DR (HLA-DR)

HLA class II histocompatibility antigen, DR (HLA-DR) is a heterodimeric cell surface receptor composed of an alpha (DRA) and a beta (DRB) chain, primarily expressed on professional antigen-presenting cells such as dendritic cells, macrophages, and B cells [UniProt: P01903]. Its fundamental biological role involves the presentation of processed exogenous peptides to CD4+ T-cell receptors, a process essential for the initiation and regulation of adaptive immune responses [PubMed: 25335454]. HLA-DR is highly polymorphic, and specific alleles are major genetic risk factors for numerous autoimmune conditions, including rheumatoid arthritis, multiple sclerosis, and type 1 diabetes [StatPearls: NBK541019]. In the context of oncology, HLA-DR is often overexpressed in certain hematologic malignancies like B-cell lymphomas, making it a viable target for monoclonal antibody-based therapies designed to induce direct cell death or antibody-dependent cellular cytotoxicity [PubMed: 11523015]. Furthermore, the level of HLA-DR expression on monocytes (mHLA-DR) is a recognized biomarker for immune competence, where low levels are associated with immunoparalysis in sepsis and trauma patients [PubMed: 16447141]. Therapeutic interventions targeting HLA-DR include peptide copolymers like glatiramer acetate, which competitively bind the HLA-DR groove to modulate T-cell reactivity in multiple sclerosis [PubChem: CID 3081362]. Experimental monoclonal antibodies also target HLA-DR to trigger apoptosis in cancerous B cells or to block unwanted immune activation in transplant rejection [PubMed: 18420825].

Other names

MHC class II antigen DRHuman leukocyte antigen DRHLA-DRBHLA-DRAMajor histocompatibility complex class II DR

Competitive inhibition of peptide binding to the MHC class II groove and induction of programmed cell death via antibody-mediated signaling.