Erythropoietic alterations in mice bearing a transplantable lymphoma

Tumor-induced changes in the pattern of erythropoiesis have been studied in A/RB mice bearing a transplantable ascites tumor, DBA lymphoma. The tumor growth was accompanied by diminished erythropoiesis, and the 51Cr-labeled red cell half-life was also decreased. Plasma iron turnover rate of the tumor bearing hosts, however, was increased and the level of erythropoietic stimulating factor (erythropoietin) in the plasma was not reduced. The existence of an inhibitor(s) to erythropoietic activity was unlikely. Comparative study of the erythropoietic activity revealed suppression in the marrow, but an increment in the spleen. The distribution of pluripotent hematopoietic stem cells (CFUs) also paralleled this alteration. However, the degree of ineffective erythropoiesis, determined by in vitro technique, was significantly elevated in the spleen. Possibly, this has reduced the effectiveness of splenic compensatory erythropoiesis.