After the absolute neutrophil count is greater than 1000/ul or after hematological nadir, leukapheresis using a continuous flow blood cell separator will be initiated. A 10-15 liter apheresis will be performed unless stopped earlier for clinical judgment of toxicity (e.g., numbness, tetany). The G-CSF will continue until apheresis is discontinued. If necessary, platelets will be transfused to greater than 60,000/ul prior to each apheresis.