Comparative effects of G-CSF, GM-CSF and IL-3 on cytosine arabinoside- and daunorubicin-mediated cytotoxicity of acute myeloid leukemia cells and normal myeloid progenitors.

We carried out an in vitro study on the combined effects of three CSF (G-CSF, GM-CSF and IL-3) plus the cycle-specific chemotherapeutic drugs [cytosine arabinoside (Ara-C) and daunorubicin (DNR)] on the proliferation and cytotoxicity of blasts and clonogenic cells (CFU-AML) in the AML-193 cell line, in AML patients and in normal bone marrow CFU-GM. The number of surviving blasts and/or DNA synthesis in blasts treated with CSF plus Ara-C or DNR was greater than those treated without CSF in the AML-193 cell line, and in some AML patients. On the other hand, the Ara-C- and DNR-mediated cytotoxicity of CFU-AML was not abrogated by CSF in any instance, but rather, it was significantly enhanced by all the CSF in the majority of instances. Although the enhancement was clearer when Ara-C was used, compared with DNR, there were no significant differences among the enhancing effects of the CSF. Under the same culture conditions as those for CFU-AML, all of the CSF significantly enhanced the Ara-C-mediated cytotoxicity of day 7 normal CFU-GM, although to a lesser extent than in CFU-AML. However, none of the CSF significantly affected the Ara-C-mediated cytotoxicity of day 14 normal CFU-GM or the DNR-mediated cytotoxicity of day 7 or day 14 normal CFU-GM. These results suggest that in the selection of a strategy entailing combined use of cycle-specific drugs plus CSF to increase the antileukemic effectiveness of chemotherapy in AML, G-CSF is preferable to GM-CSF or IL-3, since it has fewer potential clinical side effects, and that, furthermore, DNR may be as useful as Ara-C.