HLA class II histocompatibility antigen, DRB1 beta chain (Arginine-74 variant) (HLA-DRB1-Arg74)

The HLA-DRβ1-Arg74 variant is a specific isoform of the Major Histocompatibility Complex (MHC) class II beta chain, characterized by the presence of an arginine residue at position 74 (UniProt P01911). This variant, primarily associated with the HLA-DRB1*03:01 allele, is recognized as the primary genetic risk factor for autoimmune thyroid diseases (AITD), including Graves' disease and Hashimoto's thyroiditis (Jacobson et al., 2008). The Arg74 residue is strategically located within the P4 peptide-binding pocket of the HLA-DR molecule, where its positive charge facilitates the binding and presentation of pathogenic autoantigenic peptides, such as those derived from thyroglobulin or the thyroid-stimulating hormone receptor (Menconi et al., 2010). By presenting these peptides to CD4+ T-helper cells, the Arg74 variant initiates the autoimmune response that leads to the production of thyroid-stimulating antibodies and subsequent thyroid dysfunction. Research into therapeutic interventions has identified small molecules, such as C10 and cephaeline, that specifically bind to the Arg74-containing P4 pocket to block autoantigen presentation (Latif et al., 2016). This targeted approach aims to suppress the disease-specific immune response while maintaining overall immune competence, offering a potential precision medicine strategy for patients carrying this genetic risk factor.

Other names

HLA-DRB1*03:01MHC class II antigen DRB1*03Human leukocyte antigen DR beta 1 Arg74DRB1*0301HLA-DR3

Competitive inhibition of the peptide-binding groove, specifically the P4 pocket, to prevent the presentation of autoantigenic peptides (e.g., from thyroglobulin or TSH receptor) to CD4+ T-cells (Latif et al., 2016).