Long-term hematopoietic engraftment after autologous peripheral blood progenitor cell transplantation in pediatric patients: Effect of the CD34+ cell dose

Abstract

Background and Objectives: We analyzed the relationship between long-term hematopoietic recovery and the number of CD34+ cells infused in order to determine the optimal dose of CD34+ cells for rapid and stable engraftment. Patients and Methods: Between November 1993 and December 1998, 96 consecutive autologous transplantations were performed in 92 pediatric patients with different malignancies. Peripheral blood progenitor cells (PBPC) were mobilized by G-CSF alone (12μg/kg/day s.c., Neupogen®; Amgen, Thousand Oaks, Calif., USA) and collected using a Cobe Spectra blood cell separator (Cobe, Denver, Colo., USA) through a central venous catheter with double lumen. The CD34+ cell contents of apheresis products were assessed by means of flow-cytometric analysis using an Epics Elite flow cytometer (Coulter, USA). Results: The median number of CD34+ cells infused was 3.2 x 106/kg (range 0.17-44.4). The median times for short-term engraftment (neutrophil count >0.5 x 109/l and platelet count >20 x 109/l) was 9 (range: 7-16) and 13 days (range: 7-91), respectively. The median times for long-term engraftment (platelet count >50 x 109/l and >100 x 109/l) was 21 (range: 10-249) and 45 days (range: 12-288). When the infused CD34+ cell dose was ≥5 x 106/kg (median 7.99, range 5.01-44.4), there was a statistically significant increase in the rate of short- and long-term hematopoietic recovery compared to patients transplanted with a lower number of CD34+ cells (p < 0.0001). The earlier recovery in the high CD34+ cell group resulted in less transfusional support, fewer days on intravenous antibiotics and shorter hospitalization. Conclusions: This study confirms that G-CSF-mobilized PBPC provide rapid short- and long-term hematopoietic engraftment in pediatric patients undergoing autologous transplantation if a CD34+ cell dose ≥5.0 x 106/kg is infused. As this PBPC dose seems to have clinical and potentially economic implications, it should be considered the optimal dose for apheresis. Copyright (C) 2000 S. Karger AG, Basel.