THE FOLLOW-UP OF CIRCULATING HEMATOPOIETI C PRECURSOR CELL MOBILIZED WITH GRANULOCYTIC GROWTH-FACTOR (G-CSF) BY FLOW-CYTOMETRY

BACKGROUND: The aim of the present study was to investigate the charac teristics of the mobilization of hematopoietic precursor cells CD34+ i n peripheral blood following stimulation with recombinant granulocytic colony stimulating factor (G-CSF). METHODS: Fourteen patients (10 mal es, 4 females: mean age 33 years; range 14-58 years) diagnosed with on cohematologic neoplasms, in complete remission were studied. The patie nts had not received antineoplastic for at least four weeks prior to i nclusion in the study. Recombinant G-CSF (8 mu g/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 a t day +3 in 5 patients and at day +4 in 9 patients. The CD34+ cell con tent was determined in both peripheral blood and leukapheretic materia l by flow cytometry with an anti CD 34 monoclonal antibody conjugated with fluorescein. RESULTS: NO significant differences were observed be tween the mononuclear cells and CD34+ counts obtained at the first aph eresis 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), respecti vely). The content of the apheresis products in CD34+ cells correlated positively with the number of these cells circulating in peripheral b lood (r = 0.53, p = 0.001). In the second apheresis, the presence of m ononuclear 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 le ukaphesis in that the fourth apheresis only contributed in approximate ly 10% of the total quantity of CD34+ cells collected. CONCLUSIONS: Ma ximum mobilization of precursor cells was achieved on the third day at a dosis of 8 mu g/kg/day, with the data found suggesting that three l eukapheretic procedures are enough to collect most of the CD34+ cells mobilized.