Am80 promotes neutrophil differentiation more effectively than G-CSF while stimulating proliferation and preventing cell death similar to G-CSF. (A) Better granulocytic induction associated with lower monocytic induction in CD34⁺ cells treated with G-CSF for 6 versus 9 or 12 days. (B-C) Reduced concentration of Am80 (2.5nM) leads to more effective induction of granulocytic differentiation with negligible monocytic induction compared with G-CSF (B). Similar to G-CSF, 2.5nM of Am80 displayed capacity of stimulating proliferation while preventing cell death (C). (D) Overall comparison of Am80 and G-CSF under conditions found to be optimal for granulocytic differentiation. Granulopoiesis from CD34⁺ cells was assessed by light microscopy; arrows indicate examples of cells at their differentiation states. MB indicates myeloblast; PM, promyelocyte; MC, myelocyte; MMC, metamyelocyte; B, band neutrophils; S, segmented neutrophils; and MNC, monocyte (*band neutrophils, P < .03; segmented neutrophils, P < .0025).