Effect of chloramphenicol on colony formation from erythrocytic precursors.

In the present experiments, we compare the behavior of erythropoietic precursors and granulocytic precurosors exposed to chloramphenicol. Subcutaneous injection of 20 mg of chloramphenicol sodium succinate on five successive days induced a reduction in the number of erythrocytic colony-forming units (CFU-E) and erythropoietic burst-forming units (BFU-E) in murine marrow and spleen, while no change in number of granulocytic precursors (CFU-C) in murine hemopoietic organs was observed. In vitro studies demonstrated concentration-dependent inhibition of chloramphenicol or chloramphenicol sodium succinate in the colony formatin of all these precursors from murine and human bone marrow. However, erythropoietic burst formation of murine and human BFU-E was completely suppressed by the addition of chloramphenicol or chloramphenicol sodium succinate to the culture medium at therapeutic concentrations (20--40 microgram/ml). From the present results, it can be concluded that the reduced number of BFU-E in mice after injection of chloramphenicol sodium succinate resulted from the selective toxicity of chloramphenicol to BFU-E at therapeutic concentrations.