The effects of progenitor cell dose on the recovery kinetics of hematopoiesis were assessed in 34 children who underwent marrow-ablative chemotherapy with peripheral blood stem cell (PBSC) autografting. One patient was not engrafted, probably because of a low dose of reinfused cells. In 25 patients whose PBSCs were harvested after intensive chemotherapy without recombinant granulocyte colony-stimulating factor (rG-CSF), we found a significant correlation between the colony-forming unit for granulocyte-macrophage (CFU-GM) infused per kilogram of the patient's body weight and the time to achieve an absolute granulocyte count (AGC) of > 0.5 x 10(9)/L (r = -0.817, p < 0.001) or a platelet count of > 50 x 10(9)/L (r = -0.703, p < 0.001). No association was seen between the number of burst-forming units for erythroid (BFU-E) infused and the speed of hematopoietic recovery. In the other 8 patients with low progenitor yields (< 1 x 10(5) CFU-GM/kg), in vivo induction of PBSC was attempted by administering rG-CSF (250 to 1000 micrograms/m2/day). Seven-day administration of rG-CSF before each leukapheresis increased the committed (CFU-GM: 37.7-fold; BFU-E: 45.6-fold) as well as multipotent (CFU-mix: 6.8-fold) progenitors. These collected cells were cryopreserved and then reinfused. Using a model for simulating hematopoietic recovery kinetics, we suggest that cells induced by rG-CSF could speed the recovery of granulocyte or platelet counts after PBSC autografting.