Rapid identification of donor and recipient cells after allogeneic bone marrow transplantation using specific genetic markers.

The fate of the donor graft in allogeneic bone marrow transplantation, the presence of chimaerism and early relapse can be monitored by identification of the donor or recipient origin of haemopoietic cells in peripheral blood and bone marrow. We have done this by the use of highly informative locus-specific hypervariable DNA probes in two sex and blood group matched transplants. In four sex mismatched transplants the Y chromosome was identified by in situ hybridization using a biotinylated Y probe. Early engraftment by day 13 was detected in five of the six patients. Transient chimaerism occurred in half of the cases and was accompanied by the temporary appearance of the Philadelphia chromosome in one patient with chronic myeloid leukaemia without subsequent relapse. Persistence of the graft in the face of falling peripheral counts was documented in four of the six patients studied. The morphology as well as origin of the haemopoietic cells could be characterized by the Y probe analysis. In one patient, recipient lymphocytes were shown to co-exist with myeloid series of donor origin. We conclude that both techniques are highly specific, sensitive and can provide information within 24-48 h. Thus they are of value in guiding early therapeutic intervention in allogeneic transplantation.