Isolation and allelic polymorphism of cDNA clones and genomic clones of HLA-DP heavy and light chains.

From a human cDNA library constructed from consanguineous HLA-homozygous cell line AKIBA (HLA-A24, Bw52, DR2, Dw12, Cp63 Cp63: a new DP type), cDNA clones encoding the heavy and light chains of an HLA-DP Cp63 alloantigen were isolated and analyzed by restriction enzyme mapping and nucleotide sequence determination. Allelic comparisons of DP alpha and DP beta cDNA sequences showed that the amino acid sequence of the DP alpha chain was less polymorphic than that of the DP beta chain. In the DP beta chain, the polymorphic region was restricted to the beta 1 domain. We also isolated and characterized 15 genomic phage clones spanning a 74 kilobase (kb) pair of the DP region which were found to contain one DP alpha gene, one DP-like alpha gene, one DP beta gene, and one DP-like beta gene. Genomic blot analyses with different HLA-DP type cell lines using DP alpha cDNA as a probe revealed EcoRI fragment length polymorphism around the DP alpha gene.