An electron microscopic study of hemopoietic tissues in the course of Lewis lung carcinoma

Lewis lung carcinoma of C57Bl/6 mice causes a progressive anemia with reticulocytosis and splenomegaly, metastasizes to lungs, liver, and kidneys but does not invade hemopoietic tissues. The cause of this anemia is uncertain. We studied the structure of spleen and bone marrow in these tumor hosts by light and electron microscopy. Splenic congestion of the red pulp with numerous erythropoietic islands and marrow hyperplasia characterized the hemopoietic tissues of these mice, which, when coupled with other hematological parameters suggested a hemolytic condition. However, the erythropoietic response appeared to be in part ineffective as evidenced by phagocytosis of immature as well as mature red blood cells within the spleen and marrow. Thus, the condition of anemia in Lewis lung carcinoma may result from a multifactorial response of hemolysis and ineffective erythropoiesis and hemolysis.