RFLP analysis with cDNA probes for DQ/DP region in HLA identical sibling marrow transplants: lack of correlation with GvHD.

Background: The role of HLA-DP as transplantation antigen in contributing to GvHD is a matter of current debate. HLA-DP, is encoded centromeric to DR-DQ and its alleles are in weak linkage disequilibrium with the rest of the MHC; thus a certain number of HLA matched pairs could be actually DP incompatible to study a possible correlation between HLA-DP matching and GvHD, 24 HLA identical BMT/donor-recipient sibling pairs (serologically tested for HLA Class I and DR antigens) were tested for DQ and DP genes using restriction fragment length polymorphism (RFLP) analysis.
Methods: DNA extracts were digested according to a standard procedure with two different restriction enzymes (HIND III and MSP I) and hybridised with DQ (alpha and beta) and DP (alpha and beta) specific probes. Highly stringent hybridization and washing conditions were used to prevent cross-hybridizations.
Results: Twenty four out of 24 pairs proved to be DQ and DP identical. GvHD developed in 16 out of 24 (66.6%) recipients.
Discussion: These data suggest that DNa analysis of DQ-DP regions, with the probes and enzymes used, does not give predictive informations for GvHD in HLA genotypically identical pairs.