Large-volume leukapheresis in pediatric patients: pre-apheresis peripheral blood CD34+ cell count predicts progenitor cell yield.

BACKGROUND AND OBJECTIVE In children it is very important to optimize PBPC harvesting and to reduce the number of leukaphereses per patient. The value of pre-apheresis peripheral blood CD34+ cell concentration as a predictor of PBPC yield was studied in 23 pediatric patients with hematologic and non-hematologic malignancies in order to optimize duration of PBPC collection. DESIGN AND METHODS The patients underwent 25 stem-cell mobilization episodes with G-CSF alone and 40 large-volume leukapheresis procedures. Peripheral blood and harvested CD34+ cell concentrations were analyzed by means of flow cytometry. RESULTS Using linear regression analysis, a highly significant correlation was found between the peripheral blood CD34+ cell count and the CD34+ cells/kg patient body weight collected on the apheresis day (r = 0.826, p = 0.0001). The results indicate that at least 1 x 10(6)/kg CD34+ cells can be harvested during one leukapheresis procedure in all patients if the pre-apheresis blood CD34+ cell count is > or = 30/microL and a CD34+ cell target of > or = 5 x 10(6)/kg is achieved in at least 80% of patients if this value is > or = 50 CD34+ cells/microL processing a median blood volume of 438.7 mL/kg (range, 207-560) over a median time of 232.5 minutes (range, 182-376). INTERPRETATION AND CONCLUSIONS Our results suggest that the number of CD34+ cells harvested in a single large-volume leukapheresis can be predicted from the measurement of peripheral blood CD34+ cell concentration on the collection day.