Background: The aim of the present study was to investigate the characteristics of the mobilization of hematopoietic precursor cells CD34+ in peripheral blood following stimulation with recombinant granulocytic colony stimulating factor (G-CSF).
Methods: Fourteen patients (10 males, 4 females: mean age 33 years; range 14-58 years) diagnosed with oncohematologic neoplasms, in complete remission were studied. The patients had not received antineoplastic for at least four weeks prior to inclusion in the study. Recombinant G-CSF (8 micrograms/kg) was administered subcutaneously over a minimum of 4 days. Peripheral blood control were performed prior to administration of G-CSF (day 0), the third (day +3) day, and the sixth day (day +6). Daily leukapheresis was initiated at day +3 in 5 patients and at day +4 in 9 patients. The CD34+ cell content was determined in both peripheral blood and leukapheretic material by flow cytometry with an anti CD-34 monoclonal antibody conjugated with fluorescein.
Results: No significant differences were observed between the mononuclear cells and CD34+ counts obtained at the first apheresis and those performed at days +3 or +4 (32 +/- 14 x 10(9) vs 29 +/- 19 x 10(9) and 240 +/- 125 x 10(6) vs 162 +/- 160 x 10(6), respectively). The content of the apheresis products in CD34+ cells correlated positively with the number of these cells circulating in peripheral blood (r = 0.53, p = 0.001). In the second apheresis, the presence of mononuclear cells decreased approximately 20% with respect to the first, remained constant in later collections. To the contrary, a constant maintained decrease was observed in the collection of CD34+ on each leukaphesis in that the fourth apheresis only contributed in approximately 10% of the total quantity of CD34+ cells collected.
Conclusions: Maximum mobilization of precursor cells was achieved on the third day at a dosage of 8 micrograms/kg/day, with the data found suggesting that three leukapheretic procedures are enough to collect most of the CD34+ cells mobilized.