Serological and immunochemical analysis of the products of a single HLA DR-alpha and DR-beta chain gene expressed in a mouse cell line after DNA-mediated cotransformation reveals that the beta chain carries a known supertypic specificity.

Abstract
Using a mouse cell line transformed with and expressing a single HLA DR-.alpha. and DR-.beta. chain gene, evidence is presented that the product of the DR-.beta. chain gene carries a supertypic determinant, BR3, previously defined by serology. The amino acid sequence of this .beta. chain gene is determined from the DNA sequence. Another DR-associated supertypic specificity defined by monoclonal antibody MCS7 was not encoded by this DR-.beta. chain gene. This provides formal proof that a supertypic specificity can be associated with a product of a distinct DR-.beta. locus. Haplotypes sharing such specificites may be evolutionarily related.