Five commercially-available antibodies react differentially with allelic forms of human HLA-DR beta chain.

Allelic variants of HLA-DRB1 have been associated with a variety of autoimmune and infectious diseases. Although the precise molecular mechanisms by which HLA-DRB1 alleles predispose to a particular disease are currently unclear, it has been shown that mRNA expression levels of HLA-DRB1 are dependent on the different alleles. We aimed to measure HLA-DR beta chain levels in peripheral blood mononuclear cells of individuals carrying HLA-DRB1 *03:01/*04:01 and HLA-DRB1 *03:01/*15:01 alleles by western blotting, using five commercially-available HLA-DRB antibodies. We observed highly heterogeneous binding of the tested antibodies to the different allelic forms of the HLA-DR beta chain. Overall, we show that current immunological research that employs available antibodies to detect HLA-DR beta chains is biased towards detection of specific variants of the protein; this may cause significant discrepancy in quantification of protein expression in a heterogeneous human population. • RNA expression levels of HLA-DRB1 are dependent on the different HLA-DRB1 alleles. • Tested commercial HLA-DRB antibodies detect particular allelic forms of HLA-DRB1. • Novel tools are needed to study allele-specific protein expression of HLA-DRB1. [ABSTRACT FROM AUTHOR]