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

The **HLA class II histocompatibility antigen DR beta 1 chain (HLA-DRB1)** is a membrane protein encoded by the HLA-DRB1 gene, and forms part of the heterodimeric HLA-DR receptor with an alpha chain (HLA-DRA)[1][2][3][6][9]. As a component of major histocompatibility complex (MHC) class II, HLA-DRB1 is expressed predominantly on professional antigen-presenting cells, such as B lymphocytes, dendritic cells, and macrophages[1][2][6][9]. This molecule binds peptides derived from extracellular proteins and presents them to CD4+ T-helper cells, initiating adaptive immune responses and influencing both humoral and cell-mediated immunity[1][2][3][7]. The HLA-DRB1 gene is highly polymorphic, with thousands of alleles that affect antigen binding and are strongly associated with susceptibility and protection against various autoimmune diseases, infections, and some cancers[1][2][4][6]. The protein is widely used for HLA typing in transplantation and disease association studies, and plays a central role in regulating immune tolerance and autoimmunity[3][6]. If more specific drug-target interaction data or allele-specific mechanisms are required, these must be sourced from clinical immunology and pharmacology registries, as most drugs that impact this molecule act indirectly by modulating T cell activation rather than through direct binding.

Other names

HLA-DRB1HLA-DR beta chainHLA-DR β1Human leukocyte antigen DR beta 1 chainMajor histocompatibility complex, class II, DR beta 1DRB1

Modulation of antigen presentation to CD4+ T cells by blocking or altering MHC class II–TCR interaction Suppression of T-cell activation through co-stimulatory blockade Potential allele-specific peptide presentation modulation