HLA class II histocompatibility antigen, DQ alpha chain (HLA-DQA)

The HLA class II histocompatibility antigen, DQ alpha chain, is a critical component of the HLA-DQ heterodimer, a cell surface receptor found on professional antigen-presenting cells such as macrophages, B cells, and dendritic cells (UniProt P01903). Its primary biological function is the presentation of exogenous peptides to CD4+ T-helper cells, which is essential for initiating the adaptive immune response (NCBI Gene ID: 3117). Polymorphisms in the genes encoding the DQ alpha and beta chains are strongly associated with susceptibility to various autoimmune disorders, most notably celiac disease and type 1 diabetes, where specific HLA-DQ variants (like DQ2 and DQ8) mistakenly present self-antigens or harmless dietary proteins as threats (PubMed: 28864455). Therapeutic targeting of the DQ alpha chain or the resulting heterodimer is a major area of research, particularly in celiac disease, where drugs like DONQ52 aim to bind the HLA molecule to block the recognition of gluten-derived peptides (ClinicalTrials.gov). Modulating this target offers a pathway toward antigen-specific immunotherapy, potentially avoiding the side effects associated with broad-spectrum immunosuppressants.

Other names

HLA-DQA1MHC class II antigen DQA1HLA-DQA2CELIAC1DQ alpha 1 chain

Drugs targeting HLA-DQA typically function by blocking the peptide-binding groove of the HLA-DQ heterodimer to prevent the presentation of pathogenic antigens (such as gluten peptides) to CD4+ T cells, thereby inhibiting the downstream inflammatory cascade.