Human leukocyte antigen DR4 receptor (HLA-DR4)

Human leukocyte antigen DR4 receptor (HLA-DR4) is a cell surface receptor and a specific subtype of the major histocompatibility complex (MHC) class II family, encoded by the HLA-DRB1*04 alleles[3][6]. HLA-DR4 plays a critical role in the immune system by binding and presenting extracellular (exogenous) peptide antigens to CD4+ T-cells, thereby initiating T-cell-mediated immune responses[6]. The receptor is highly polymorphic, and certain variants (notably those encoding the so-called "shared susceptibility epitope") are strongly associated with increased risk of autoimmune disorders, particularly rheumatoid arthritis and type 1 diabetes[7][9][8]. HLA-DR4 forms a heterodimer with a matched alpha (DRA) and beta (DRB1*04) chain, both anchored in the membrane of antigen-presenting cells such as B lymphocytes, dendritic cells, and macrophages[6][1]. The beta chain contains the principal sites of polymorphism that define binding specificity and modulate disease risk. The association of HLA-DR4 with pathological immune responses makes it both a critical biomarker and a therapeutic consideration in autoimmunity. However, directly targeting HLA-DR4 therapeutically is limited by its essential role in normal immune surveillance and the risk of immunosuppression[7][9][8].

Other names

HLA-DR4DR4DRB1*04HLA-DRB1*04

Modulation of antigen presentation to CD4+ T cells; Immune inhibition or alteration via blockade of T-cell co-stimulation or B-cell targeting (Note: listed drugs affect T-cell activation or immune processes involving HLA-DR4, not HLA-DR4 directly).