Erythropoiesis in mice with chemically-induced tumor

The erythropoietic response of Strain A mice with benzo(a)pyrene-induced fibrosarcoma has been studied. The rate of erythropoiesis, expressed in terms of 59Fe incorporation into circulating erythrocytes, was slightly increased in the fibrosarcomatous mice compared to the matched controls. The femoral marrow of the tumor hosts became hypocellular with reduced number of erythroblasts. The spleen, on the other hand, was hypercellular with an increased number of erythroid progenitor cells. Quantitative assessment of erythropoietic activity in the hematopoietic organs by measuring the 6-hr organ uptake of 59Fe revealed erythropoietic suppression in the marrow but enhancement in the spleen following tumor development. While the number of CFU-s in the femoral marrow of the tumor-bearing animals was slightly increased, marked increase in the concentration as well as absolute number of CFU-s was found in the spleen. Bioassay for erythropoietin revealed appreciable increase in the level of plasma erythropoietin in the tumor-bearing animals.