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 progenito r cell (PBPC) harvest protocol to provide support for repetitive chemo therapy 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 wit h an autologous bone marrow transplant. Progenitor cell content was ex amined in the context of hematopoietic engraftment. Results: Mobilizat ion allowed the harvest of large numbers of PBPCs. Peak harvests tende d to occur after the recovering white cell count exceeded 10 x 10(9) p er L. CD34+ lymphomononuclear cell (MNC) and colony-forming units-gran ulocyte-macrophage (CFU-GM) counts correlated poorly, but both measure s peaked within 24 hours of each other in 21 of 26 patients, which dem onstrated 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 e nsure engraftment could be derived. Conclusion: Cyclophosphamide and G -CSF allowed the harvest of sufficient PBPCs to support multiple round s 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 m ay allow harvest protocols to be tailored to individual patients.