Factors Influencing Yields of Progenitor Cells for Allogeneic Transplantation: Optimization of G-CSF Dose,Day of Collection,and Duration of Leukapheresis

Mobilization of hematopoietic progenitor cells by G-CSF was attempted on 89 occasions in 85 healthy donors. Three dose ranges of G-CSF were chosen for analysis: low (4–7.4 μg/kg), intermediate (7.5–10 μg/kg) and high (>10 μg/kg). A target blood level for apheresis of 20 × 106/L CD34+ cells was reached by day 3 in 75 patients (84%) and by day 4 in all but 1 (99%). Target yields above 2.5 × 10⁶/kg for 75 unmanipulated transplants were exceeded in a single collection in 73 donors (97%). Correlation of CD34+ cell yields to blood CD34+ cell level before leukapheresis was moderate only (r² = 0.32). There was close linear correlation between processed volume and cumulative CD34+ cell yield, with a median r² value of 0.98 (range 0.74–1.00). Yields of CD34+ cells achieved on day 3 were significantly lower after the high dose than after the intermediate G-CSF dose (21 ± 3 versus 29 ± 6 × 10⁶/L blood processed, p = 0.03). After the low dose of G-CSF, yields on day 4 were higher than on day 3 (48 ± 10 versus 22 ± 4× 10⁶/L blood processed, p = 0.01). There was no difference between day 3 and day 4 yields with the intermediate G-CSF dose. In 73 of 93 (78%) leukaphereses, the CD34+ cell yield was more than 100% of the estimated intravascular CD34+ cells at the beginning of collection and ranged up to 342%. These data indicate that a daily dose of 7.5–10 μg/kg G-CSF, given as a multiple of 300 and 480 μg ampoules, is a convenient regimen giving adequate yields from a single collection on day 3 or 4 in most donors. Measuring blood CD34+ cell levels is of limited value in predicting yields, but monitoring CD34+ cell yields during leukapheresis may help to minimize unnecessary or inefficient collection.