Slow platelet recovery after PBPC transplantation from unrelated donors.

The effects of the composition of PBPC grafts from matched related donors (MRDs) and matched unrelated donors (MUDs) have not been compared. In a single-center study, the compositions of 55 MRD PBPC grafts and 33 MUD grafts were studied for their effect on the rate of engraftment in patients who had evidence of donor cell engraftment on day +28. The MUD grafts came more frequently from young male donors and contained more CD34(+) cells but similar numbers of colony-forming units granulocyte-macrophage (CFU-GM) and burst forming units-erythroid. The recovery of neutrophils to >500/mm(3) was equally fast in both groups, but recovery of platelets to >20,000/mm(3) was significantly delayed in the MUD group (P<0.001). The MUD group also required more transfusions of platelets and red cells. Patients receiving grafts containing low numbers of CFU-GM had markedly delayed platelet recovery. The patients with the slowest engraftment tended to have prolonged transportation times. Storage experiments suggested a major loss of viable CD34(+) cells and CFU-GM when undiluted PBPC products are stored at room temperature. The data suggest that a fraction of the MUD grafts suffer during transportation. In vitro proliferation assays should be part of the validation and auditing of transportation of MUD grafts.