Genomic hybridization with class II transplantation antigen cDNA probes as a complementary technique in tissue typing.

Hybridizations of HLA-DR and DC transplantation antigen beta chain cDNA probes to restriction enzyme digested genomic DNA were examined in regard to their potential in tissue typing. DNA from cells, typed by cellular techniques to be homozygous for the specificities Dw 1 to 8, gives rise to unique fragment patterns for each specificity. Hybridizations to DNA from unrelated individuals serologically typed to be DR identical occasionally reveal genetic differences in the class II antigen region, notably with the DC beta cDNA probe. In contrast, hybridizations to DNA from monozygotic twins displayed completely identical patterns with both types of probes. From these data it seems reasonable to conclude that genomic hybridizations with class II antigen probes will be useful in the definition of new class II antigen loci and alleles, in determination of paternity, in studies of class II antigen linked diseases and as a complementary method in conventional tissue typing.