Comparison of CFU-GM response to piperazinedione versus cyclophosphamide in normal mice.

The effects of cyclophosphamide and piperazinedione on marrow granulocyte-macrophage precursor (CFU-GM) cells were compared in a mouse model. Endogenous colony-forming unit ( ECFU -S) assays after drug exposure were utilized in selecting doses of the two drugs with approximately equal hematopoietic stem cell ablative potential. The selected doses were 20 mg/kg of piperazinedione and 325 mg/kg of cyclophosphamide. Injection of these doses resulted in an initial (3-h) marrow CFU-GM depression of 90% in the cyclophosphamide-treated mice and 98% in the piperazinedione-treated mice. Recovery began within 6-24 h and proceeded in a similar fashion for both groups of animals, peaking at levels near normal control values for CFU-GM at three days after exposure. Both groups showed a subsequent decline to a second nadir at nine days followed by a second recovery toward normal levels. The data suggest that the two drugs affect the CFU-GM in a similar fashion.