AII-Trans-Retinoic-Acid- and Growth-FactorMediated Induction of Alkaline Phosphatase Activity in Freshly Isolated Chronic Myeloid Leukemia Cells

Reduced or absent neutrophil alkaline phosphatase (NAP) activity is a common feature of neutrophilic granulocytes from patients with chronic myeloid leukemia (CML). In this study we examined whether NAP activity could be restored in vitro by stimulating CML cells with different promoters such as all-trans-retinoic acid (ATRA), granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF). The results obtained indicated that ATRA and G-CSF, either alone or in combination, were effective in inducing NAP activity in CML cells, whereas GM-CSF was not. Further, NAP restoration in ATRA- and G-CSFtreated cultures was accompanied by increased morphologic differentiation of the CML clone. It might be concluded that the CML clone could be driven in vitro by ATRA and G-CSF both to achieve granulocytic maturation and to correct functional NAP-related defects.