Cloning and Sequence Analysis of the DRβ Gene Coding for the Specificity HLA D/DR BON

We described a new HLA-DR specificity, called provisionally DR-BON, which was defined by cellular typing (1). At the present time no specific anti-BON serologic reagent has been found. This specificity is strongly associated with DQw1 and frequently with B35 and C4A4,C4B2. After immunoprecipitation with monomorphic anti-DR monoclonal antibodies, biochemical analysis by two-dimensional gel has shown that the BON haplotype directs the synthesis of a single DRβ chain, which is the more acidic known β chain, whereas the expressed a chain remains the classical DRα polypeptide (2). In contrast, RFLP studies with seven enzymes revealed identical patterns between DRβ and DRα genes present in DR1 and DR-BON haplotypes (2). DNA analysis also demonstrated the presence of two DRβ genomic genes in this haplotype.