Effect of Cytotoxic Agents on the Maturing Granulocytic and Erythroid Cells of Rats

Abstract

The mobilization of granulocytes from the bone marrow by endotoxin and the incorporation of ⁵⁹Fe into hemoglobin-synthesizing cells were used to measure the effect of cytotoxic agents on maturing hematopoietic cells. The recovery of maturing granulocytes was delayed, and no overshoot to greater-than-normal values was observed with dimethylmyleran which damaged the earlier repopulating stem cells. Recovery of the maturing erythroid cells was relatively independent of the depression of repopulating cells. The sensitivity of the maturing granulocytic and erythroid cells was similar for the agents studied except actinomycin D where there was no effect on maturing granulocytes at doses which completely suppressed erythropoiesis. The results show that the sparing of the repopulating cells relative to maturing cells is even greater for the granulocytic cells than for erythroid cells.