Regulation of erythropoiesis. 18. The effect of vincristine and erythropoietin on bone marrow.

Abstract

Studies are presented on the hematopoietic response of rats to vincristine and the effect of erythropoietin in red cell production in these animals. Mega- karyocytes appeared to be relatively unaffected during the period of observation, which was interpreted as indicating that there was continued differentiation of precursors into this compartment. There was a striking depopulation of the erythroid elements between the 2nd and 4th days during which differentiation of precursors could not be achieved even with massive doses of erythropoietin. Continued differentiation of cells into the megakaryocytic compartment but not the erythroid compartment suggests different immediate precursor cells; a model for this is presented and discussed. In the hypertransfused vincristine-treated rat there was a delayed response to erythropoietin. It is suggested that the immediate precrusor cells for the erythroid compartment are capable of storing information imparted by erythropoietin until such time as regeneration permits differentiation. Morphologic evaluation of the bone marrow suggests that even after recovery has proceeded to a point at which differentiation once again occurs, there is residual damage that leads to ineffective erythropoiesis.