PCR-fingerprinting for selection of HLA matched unrelated marrow donors. Collaborating Centres in the IMUST Study.

HLA typing contributes to the delays that occur in the search for HLA-matched unrelated marrow donors, and that result in poor patient survival. A new DNA technique for testing DR match between patient and unrelated marrow donors has been assessed. The technique is based on the formation of heteroduplexes between heterologous amplified coding and non-coding DNA sequences during the final annealing stage of the polymerase chain reaction (PCR), and different HLA-DR/Dw types give unique banding patterns ("PCR fingerprints") on non-denaturing polyacrylamide gel electrophoresis. HLA-DR matching is by visual comparison of patients' with donors' fingerprints. Identity can be confirmed by mixing donor and recipient DNA before the final stage of the PCR ("DNA crossmatching"). In an assessment of the technique in 53 unrelated HLA-A and HLA-B matched patient-donor pairs, 42 pairs gave the same results with PCR fingerprinting as with DNA-RFLP analysis. In the 11 other pairs DR/Dw mismatches were detected by PCR fingerprinting but not by the standard DNA-RFLP method; PCR-SSO typing with selected sequence-specific oligonucleotides (SSO) confirmed that mismatches were due to different subtypes of DR4. PCR fingerprinting might thus accelerate the selection of unrelated marrow donors by simplifying the logistics of the donor search.