BIOCHEMICAL-ANALYSIS OF HLA-DP GENE-PRODUCTS BY ISOELECTRIC-FOCUSING AND COMPARISON WITH CELLULAR AND MOLECULAR-GENETIC TYPING RESULTS

The polymorphism of HLA-DPA1 and HLA-DPB1 genes of 39 lymphoblastoid c ell lines, representing 3 DPA1 and 14 DPB1 alleles, was studied after immunoprecipitation of DP molecules, subsequent isoelectric focusing ( 1D-IEF) and immunoblotting by a polyclonal DP antibody. Two ID-IEF var iants for DPA1 and 7 for DPB1 gene products were identified, including 2 new variants associated with the DPB11401 and DPB1*1901 alleles. T he 1D-IEF polymorphism correlated clearly with molecular-genetic-defin ed alleles and primed lymphocyte or T cell line (PLT) specificities wi th exceptions observed in DUCAF (DPB10202) and ARBO (DPB1*0101). Both exceptional cases may reflect amino acid variations outside the hyper variable regions (HVRs) at the second exon of DPB1. The findings were supported by a comparison of HVR amino acid sequences with estimated n et charges to the isoelectric points of the DPB1 molecules. 1D-IEF see ms to be a valuable method for studying the expression of DPA1 and DPB 1 alleles provided the molecules differ in their isoelectric points.