Cell kinetic effects of granulocyte colony-stimulating factor on the sensitivity of nonlymphocytic leukemia cells to cytosine arabinoside.

We measured the percentage of proliferating cells in peripheral blood and bone marrow of patients with nonlymphocytic leukemia by flow cytometry and immunostaining with antibodies to proliferating cell nuclear antigen (PCNA) and Ki-67. We evaluated the effects of granulocyte colony-stimulating factor (G-CSF) on nonlymphocytic leukemia cells. The S phase cell ratio, PCNA positive cell ratio, and Ki-67 positive cell ratio were higher after culture with G-CSF than culture without G-CSF. The ratio of viable cells was lower after culture with G-CSF followed by cytosine arabinoside (Ara-C) than culture with Ara-C alone. The number of clonogenic leukemic cells in methylcellulose was also smaller after culture with G-CSF followed by Ara-C than Ara-C alone. Our results suggest that the administration of G-CSF before induction chemotherapy enhances the sensitivity of antitumor agents against leukemic cells.