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 hematopoietic progenitors are essential for peripheral blood stem cell transplantation after myeloablative high-dose chemotherapy. Conflicting data have been published concerning the most useful, cost-effective collection strategy which is also convenient for patients. Materials and Methods: A total of 66 leukaphereses in 20 patients were retrospectively evaluated. We assessed the predictive value of the number of white blood cells, mononuclear cells (MNCs) and CD34+ cells in peripheral blood for the yield of CD34+ cells in leukapheresis products. The concentrations of MNCs and CD34+ cells were quantified simultaneously by a flow cytometric procedure using fluorescent microparticles. Their collection efficiencies were calculated based on a newly developed 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 least 30 CD34+ cells/μl peripheral blood was a good predictor that a single leukapheresis would yield a minimum of 2.0x10⁶ 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. (C) 2000 S. Karger AG, Basel.