Colony Stimulating Activities of GM-CSF, G-CSF and IL-3 on Blast Progenitors from Acute Myeloblastic Leukemia

The colony stimulating activities (CSAs) of recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF), recombinant granulocyte colony-stimulating factor (rG-CSF) and recombinant interleukin-3 (rIL-3) on blast cells from various types of acute myeloblastic leukemia (AML) patients were studied using an in vitro blast colony assay. The stimulatory magnitude of rGM-CSF was highest in type M4 blasts but almost non-existent in type M1 blasts. Some preferential stimulatory action of rG-CSF was observed in type M2, M4 blasts and in overt leukemia in patients with refractory anemia with excess of blasts. On the other hand, the stimulatory activity of rIL-3 did not differ much with the AML subtype. Exposure to rGM-CSF, rG-CSF or rIL-3 did not alter the cellular phenotype or morphology of the leukemic blasts or the self-renewal capacity of blast progenitors. Simultaneous addition of rGM-CSF, rG-CSF and rIL-3, in various combinations, produced variable results and a simple additive effect was seen in 40% of the cases studied and either a significantly larger or smaller value in the remaining cases. Recombinant GM-CSF, rG-CSF and rIL-3 when added together did not reconstitute CSA of phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM).