Associations among white blood cells, CD34+ cells and GM-CFU in predicting the optimal timing of peripheral blood stem cell collections by apheresis.

ABSTRACT

AIMS: To analyze preapheresis blood CD34+ cells and corresponding apheresis products in order to investigate whether peripheral blood CD34+ cell counts correlate with peripheral blood progenitor cell (PBPC) yields and to determine the optimal timing for starting PBPC collections in our clinical setting. MATERIAL AND METHODS: Thirty-eight patients with hematological malignancies and undergoing varied mobilization regimens were enrolled. White blood cell counts (WBC), CD34+ cells and granulocyte-macrophage colony-forming units (GM-CFU) enumeration were performed on blood samples taken immediately prior to each apheresis procedure and in the corresponding PBPC collection. Results: A total of 61 apheresis procedures were performed, with a median of two collections per patient (range 1-3). The number of CD34+ cell/ml in the preapheresis blood correlated closely with CD34+ cells/kg and, to a lesser degree, with GM-CFU/kg in the apheresis products (r = 0.81 and r = 0.67, respectively, P < 0.0001). WBC showed significant but poor correlation with CD34+ cells/kg and GM-CFU/kg (r = 0.43 and r = 0.45, respectively, P = 0.004). A significant correlation was also found between CD34+ cells/kg and GM-CFU/kg in PBPC collections (r = 0.62, P < 0.0001). Linear regression analysis indicated that the minimum threshold of 2 x 10(6) CD34+ cells/kg might be attained with a single apheresis if the CD34+ cells/ml in the peripheral blood measured prior to apheresis on the day of collection is > or =26 x 10(3) CD34+ cells/ml. CONCLUSION: Collectively, these data demonstrate that circulating CD34+ cells is more useful than GM-CFU or WBC for predicting the optimal timing of PBPC harvests.