| Abstract: | The effect of in vivo administration of actinomycin D (Act D) on the hemopoietic precursor compartments and, in particular, the BFU-E, CFU-E, and erythroblast populations was investigated over a 6-day period. Daily injections of mice with 15 microgram/kg, 30 microgram/kg, and 60 microgram/kg Act D showed a dose-dependent effect. The highest dose caused an almost complete eradication of CFU-E as well as the morphologically identifiable erythroblasts. There was no appreciable reduction in BFU-E, GM-CFU, and CFU-S. These observation indicate that Act D interferes with erythropoiesis by selectively inhibiting the CFU-E compartment. The effects are not due to altered sensitivity to erythropoietin as dose response curves were similar for control and Act D-treated cells. Although a considerable reduction in CFU-E is observed and approximately 20-30% of nucleated cells are lost from the small size region, there is no displacement in the velocity sedimentation profiles either from the remaining CFU-E and nucleated cell populations or the BFU-E and GM-CFU populations. |
