Polymorphism of the HLA-DP beta region detected by Southern blot hybridization.

A panel of homozygous cell lines, previously typed by primed lymphocyte test for their DPw specificity, have been studied by restriction fragment length polymorphism analysis, using a DP beta-specific probe. Highly stringent hybridization and washing conditions were used to prevent cross-hybridization with DR- and DQ-specific fragments. Three out of six enzymes employed allowed us to distinguish clustered or single DPw specificities, and by MspI digestion it was possible to detect different patterns within a single specificity such as DPw4. Some of the cell lines have been further studied with synthetic oligonucleotides derived from the polymorphic regions of the second exon of DP beta 1 gene, and, in general, a correlation with the primed lymphocyte test--defined specificities and restriction fragment length polymorphism was found. These data suggest a more extended complexity of the DP region, in addition to that defined as the DPw1-DPw6 segregant series.