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

HLA class II histocompatibility antigen, DRB1 beta chain (HLA-DRB1) is a critical component of the major histocompatibility complex (MHC) class II heterodimer, which functions as a cell surface receptor on antigen-presenting cells. Its primary biological role is to present exogenous peptides to CD4+ T cells, thereby initiating and regulating adaptive immune responses [1.2.3, 1.4.1]. Specific alleles, most notably HLA-DRB1*04:01, contain a conserved sequence known as the 'shared epitope' (SE) that is the most significant genetic risk factor for rheumatoid arthritis (RA) [1.2.2, 1.4.4]. This epitope facilitates the presentation of citrullinated self-antigens, leading to the production of anti-citrullinated protein antibodies (ACPAs) and chronic synovial inflammation [1.3.3, 1.4.3]. While HLA-DRB1 is not a traditional target for small-molecule inhibition, it serves as a vital biomarker for predicting disease severity and the efficacy of disease-modifying antirheumatic drugs (DMARDs) like methotrexate and abatacept [1.1.2, 1.5.1]. Emerging therapeutic strategies aim to specifically block the shared epitope's pro-inflammatory signaling or use peptide-based vaccines to induce immune tolerance in HLA-DRB1*04:01-positive patients [1.1.4, 1.5.2].

Other names

Major histocompatibility complex, class II, DR beta 1HLA-DRB1*04:01Shared epitopeMHC class II antigen DRA/DRB1Lymphocyte antigen DRB1HLA-DR1BHuman leukocyte antigen DRB1

Modulation of the immune synapse and T-cell activation; experimental competitive inhibition of shared epitope-mediated signaling via calreticulin.