HLA-DPB1 typing by PCR-SSO reverse dot blot hybridization after group-specific amplification.

Background: The allelic diversity of HLA-DPB1 antigens can be determined at the DNA level after PCR amplification. The pattern of polymorphism at the DPB1 locus makes it difficult to unambiguously assign all genotypes in a typing system using one single pair of generic primers.

Materials and methods: We apply here a simple technique based on the reverse dot blot analysis to the typing of HLA-DPB1 alleles. In order to increase its resolution, a group-specific amplification based on sequence variations of the polymorphic region F was used subdividing the HLA-DPB1 alleles in 2 nonoverlapping families. A separate analysis was then performed within each group of alleles.

Results: Using these 2 primer pairs, 21 group 1 and 30 group 2 alleles were separately amplified. From 1,378 possible allele combinations for DPB1*0101-5301 only 33 gave ambiguous typing results compared to 61 using a single pair of generic primers.

Conclusions: This procedure provides a rapid and simple HLA-DPB1 genotyping. Especially in heterozygotes the hybridization patterns were easier to interpret. The utilization of group-specific amplification substantially reduced ambiguous typing results.