New family of exon-shuffled recombinant genes reveals extensive interdomain interactions in class I histocompatibility antigens and identifies residues involved

The specificities of an extensive panel of anti-H-2D(d) monoclonal antibodies, which had been previously characterized using exon-shuffled H-δ(d)/H-2L(d) molecules and a number of anti-H-2D(p) antibodies, were examined using H-2D(d)/H-2D(p) recombinants. The use of this new family of recombinant antigens revealed extensive interaction between the membrane-distal (N and C1) domains of class I molecules, 20 out of 48 mAbs recognize complex epitopes formed by the interaction of these two domains. These antibodies exhibit a number of distinct patterns of crossreactivity with other class I proteins, revealing the presence of multiple epitopes within the region of domain interaction. Comparison of the data presented here with those from previous work allowed the identification of a small number of residues in the C1 domain that participate in the generation of complex epitopes involving both the N and C1 domains. The results are discussed in terms of the structural information available for these two domains.