Polymorphism of the HLA-DPβ 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 DPβ-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 DPβ1 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.