Summary:Since early studies demonstrated the feasibility of hematopoietic reconstitution by infusion of peripheral blood stem cells (PBSC), 1-4 autologous PBSC transplantation has We infused peripheral blood stem cells (PBSC) into 51 patients with various malignant disorders, after myebecome an established procedure in clinical oncology. In many centers, including our own, the majority of autololoablative conditioning. Twenty-four patients also received autologous bone marrow (PBSC + BM). In a gous transplantation procedures now employ stem cells harvested from peripheral blood rather than bone marrow. multivariate analysis, the only statistically significant predictors of neutrophil engraftment were log-dose PBSC transplantation offers several advantages over autologous bone marrow transplantation. PBSC collection by CFU-GM (P Ͻ 0.001) and the number of prior chemotherapy regimens (P = 0.004). The factors predicting apheresis involves less trauma to the patient than bone marrow aspiration and enables autologous hematopoietic RBC and platelet engraftment were log-dose CFU-GM (P = 0.002), PBSC + BM infusion (P = 0.007) and the reconstitution in cases in which metastasis, fibrosis or postradiation acellularity precludes marrow harvesting. Moreabsence of neoplastic bone marrow involvement (P = 0.009). Seven patients remained platelet and/or red cell over, there is evidence that PBSC engraft more rapidly than autologous marrow stem cells, 5-9 with the potential benefits transfusion-dependent for 100 days or more post-transplant after good neutrophil recovery. Six of these seven of reduced post-transplantation morbidity and a shorter hospital stay. long-term engraftment failures, as well as five additional patients, received Ͻ10 5 CFU-GM/kg. Of the 11 patients PBSC transplantation is not, however, without disadvantages. Under physiological conditions, peripheral blood who received Ͻ10 5 CFU-GM/kg (low-dose patients), seven were PBSC recipients, of whom six were longcontains far fewer stem cells than bone marrow. 10,11 Chemotherapeutic agents 12-16 and/or hematopoietic growth facterm engraftment failures. In contrast, there were no long-term engraftment failures among the four low-dose tors 5-9 may be used to mobilize stem cells from the marrow into the peripheral blood, but there is significant morbidity autologous marrow recipients. This difference in longterm engraftment failure rate was significant (P = associated with the use of these agents. Even with stem cell mobilization, multiple apheresis and cryopreservation 0.015). The low-dose PBSC patients all had a diagnosis of lymphoma with bone marrow involvement. The lowprocedures are required in the majority of cases to obtain adequate numbers of stem cells for hematopoietic reconstidose PBSC + BM group was more heterogeneous, but no patient had malignant involvement of the marrow.tution. There is also a concern that PBSC may be inferior to marrow stem cells in terms of their long-term repopulating The low-dose PBSC patients had also received significantly more pri...