Polymorphism in the promoter region of HLA-DRB genes.

Polymorphism is a hallmark of the molecules encoded within the MHC of humans and other mammals. Recently, evidence of polymorphism has also been shown to exist in the transcriptional regulatory regions of HLA-DQB genes. In this article, we report that polymorphism exists also in the promoter region of HLA-DRB genes. The sequence of the regulatory region of DRB genes from five homozygous DR B-cell lines, each of a distinct DR haplotype, revealed a number of differences, some of which are in the critical class II boxes that are generally conserved in class II promoters. The major differences occurred in a comparison of DR4 to the other DR haplotypes. These data suggest the existence of another important source of HLA class II polymorphism that may play a role in susceptibility to HLA-associated autoimmune disease.