HLA class II histocompatibility antigen, DR beta 1 chain (HLA-DRB1)

HLA class II histocompatibility antigen, DR beta 1 chain (HLA-DRB1) is a fundamental component of the Major Histocompatibility Complex (MHC) class II, primarily expressed on professional antigen-presenting cells such as B cells, macrophages, and dendritic cells (UniProt P01911). It functions by forming a heterodimer with the HLA-DRA chain to create a groove that binds and presents exogenous peptides to CD4+ T-helper cells, thereby initiating the adaptive immune response (PubMed: 3591864). HLA-DRB1 is characterized by extreme polymorphism, with specific alleles like the 'shared epitope' being strongly associated with the risk and severity of rheumatoid arthritis and multiple sclerosis (PubMed: 21833088). In clinical practice, it is a key therapeutic target for glatiramer acetate, which acts as a decoy peptide competing for the HLA-DRB1 binding groove to modulate the inflammatory environment in multiple sclerosis (PubMed: 17355198). Furthermore, monoclonal antibodies targeting HLA-DR have been developed for the treatment of certain B-cell malignancies by inducing direct cell death or immune-mediated depletion. Monitoring HLA-DR expression on monocytes is also utilized as a clinical biomarker for immune competence in patients with sepsis or major trauma (PubMed: 16401920).

Other names

Major histocompatibility complex, class II, DR beta 1MHC class II antigen DRB1*1DR-beta-1Lymphocyte antigen DRB1SS1

Competitive inhibition of the peptide-binding groove; Monoclonal antibody-mediated cell depletion (ADCC/CDC); Induction of apoptosis in HLA-DR-expressing malignant cells; Blockade of co-stimulatory signals between MHC-II and T-cell receptors.