Clinical protocol. Healthy donors for allogeneic stem cell transplantation were treated with a single dose of AMD3100 (240 μg/kg) and, following a 1-week washout period, with 5 days of daily G-CSF (10 μg/kg/d). Leukapheresis was initiated 4 hours after AMD3100 and 5 days after G-CSF treatment. Peripheral blood was drawn prior to AMD3100 treatment (baseline) or immediately prior to each leukapheresis.