Effect of bleomycin on mouse haemopoietic colony forming cells in culture (CFUc)

The kinetics of CFUc studied by hydroxyurea and endotoxin treatments indicate that this cell population is proliferating actively (some 50% in S-phase). This fact implies a peculiar response to (BLM) treatment with Bleomycin, a drug which appears to be proliferation-dependent. The dose-response has a steep initial slope resulting in a low extrapolation number (n = 0.66; D37 = 960 +/- 70 mg BLM/kg body weight). The steep initial slope is confirmed by split-dose experiments resulting in a potentiation effect by fractionation. Further evidence for the dependence of the action of this drug upon the proliferative state of the cell population is derived from time-response studies after single doses of BLM.