THE COLLECTION AND EVALUATION OF PERIPHERAL-BLOOD PROGENITOR CELLS SUFFICIENT FOR REPETITIVE CYCLES OF HIGH-DOSE CHEMOTHERAPY SUPPORT

Background: The development of an optimized peripheral blood progenitor cell (PBPC) harvest protocol to provide support for repetitive chemotherapy cycles is described. Study Design and Methods: PBPCs mobilized by cyclophosphamide plus granulocyte-colony-stimulating factor (G-CSF) were studied in 163 leukapheresis harvests from 26 lymphoma patients. Harvested cells were transfused with two chemotherapy cycles and with an autologous bone marrow transplant. Progenitor cell content was examined in the context of hematopoietic engraftment. Results: Mobilization allowed the harvest of large numbers of PBPCs. Peak harvests tended to occur after the recovering white cell count exceeded 10 x 10(9) per L. CD34+ lymphomononuclear cell (MNC) and colony-forming units-granulocyte-macrophage (CFU-GM) counts correlated poorly, but both measures peaked within 24 hours of each other in 21 of 26 patients, which demonstrated PBPC mobilization. Engraftment of platelets (>50 x 10(9)/L) and granulocytes (>500 x 10(6)/L) was achieved in a median of 20.5 and 16 days, respectively. A minimum number of progenitors necessary to ensure engraftment could be derived. Conclusion: Cyclophosphamide and G-CSF allowed the harvest of sufficient PBPCs to support multiple rounds of chemotherapy Harvest should commence when the recovery white cell count exceeds 10 x 1O(9) per L. PBPC harvest CD34+ MNC counts are as useful as CFU-GM results in the assessment of PBPC content, and they may allow harvest protocols to be tailored to individual patients.