Collection efficiencies of CD34+progenitor cells and mononuclear cells in leukapheresis products quantified by flow cytometry and calculated on the basis of a new formula

Background and Objectives: Optimal mobilization and harvest of hematopoieti c progenitors are essential for peripheral blood stem cell transplantation after myeloablative high-dose chemotherapy. Conflicting data have been publ ished concerning the most useful, cost-effective collection strategy which is also convenient for patients. Materials and Methods: A total of 66 leuka phereses in 20 patients were retrospectively evaluated. We assessed the pre dictive value of the number of white blood cells, mononuclear cells (MNCs) and CD34+ cells in peripheral blood for the yield of CD34+ cells in leukaph eresis products. The concentrations of MNCs and CD34+ cells were quantified simultaneously by a flow cytometric procedure using fluorescent microparti cles. Their collection efficiencies were calculated based on a newly develo ped formula. Results: The collected hematopoietic progenitor concentration could be predicted only by the number of peripheral blood CD34+ cells prior to apheresis (r = 0.902; p<0.01). Furthermore, the mobilization of at leas t 30 CD34+ cells/mu l peripheral blood was a good predictor that a single l eukapheresis would yield a minimum of 2.0x10(6) CD34+ cells/kg body weight. The collection efficiencies calculated by the new formula were 55.2+/-10.7 % and 57.7+/-11.2% for MNCs and CD34+ cells, respectively. Conclusion: The precise quantification of MNCs and CD34+ cells by a direct flow cytometric assay, as well as the new formula to determine the collection efficiencies, has an impact on optimizing high-quality stem cell products. Copyright (C) 2000 S. Karger AG, Basel.