Effect of arabinosyl cytosine on granulopoietic colony formation by marrow cells from leukemic and non-leukemic patients.

This study investigated the arabinosyl cytosine (ara-C) sensitivity of colony formation in culture by human granulopoeitic progenitor cells (CFU-C). Wide variations were observed in the effects of ara-C on CFU-C from the marrow of patients with leukemia in remission after treatment using a chemotherapeutic regimen that included ara-C, or for CFU-C from the marrow of non-leukemic patients. These variations in sensitivity to ara-C could not be attributed to a lack of reproducibility of the culture conditions used, nor to variations in the proliferative state of the CFU-C at the time of exposure to ara-C. No significant correlation was observed between the sensitivity of CFU-C to ara-C and the level of cytidine deaminase in the marrow sample. These results provide some support for the view that cell kill may not be the only basis for the chemotherapeutic effectiveness of ara-C.