Predictive parameters for mobilized peripheral blood CD34+ progenitor cell collection in patients with hematological malignancies

In order to investigate what is the best single parameter to predict the leukapheretic yield of circulating CD34+ progenitor cells, we retrospectively analyzed data from 68 patients with hematological malignancies who underwent mobilizing therapy. Three main parameters were monitored: total white blood cell (WBC), CD34+ cells, and monocyte counts in peripheral blood (PB) at the same day and at the preceding day of the apheretic procedure. Linear regression analysis revealed a strong correlation between CD34+ cell value in PB just before harvest and the number of CD34+ cells collected (P < 0.0001), but not at the preceding day. Monocyte PB concentration and absolute WBC count did not correlate with CD34+ cells harvested, at the preceding day of leukapheresis as well as at the same day of the procedure. The number of CD34+ cells in mobilized PB at the same day of harvest evidenced a very good capacity of predicting the value of harvested CD34+ cell number after collection, while WBC and monocyte count displayed quite a wide dispersion of results. In particular, an amount greater than 50/microL of circulating CD34+ cells ensured the best collections. Finally, CD34+ and CFU-GM content evaluated for each apheresis showed a strong reciprocal correlation (r 0.78; P < 0.0001). We conclude that the absolute number of CD34+ cells at the day of leukapheresis is the only parameter for identifying the exact timing for apheresis and predicting the amount of peripheral blood progenitor cells (PBPCs) that will be collected. In this setting, WBC and monocyte counts, at the day of collection or at the preceding day, are not useful tools.