Host-tumor interactions: basis for the anemia in rats bearing the hepatoma 7777.

A significant anemia develops in Buffalo rats bearing the Morris hepatoma 7777. By indiceal measurements the red blood cells (RBCs) appear to be microcytic and hypochromic. Ferrokinetic studies demonstrate a decreased uptake of iron in the bone marrow and an increased incorporation of iron in the spleens of the tumor-bearing animals. RBC survival studies indicate the presence of a hemolytic component which appears to contribute to the anemia. The RBCs from tumor-bearing animals (T-RBC) have a greatly increased fragility in sodium chloride solutions. Inspection of these T-RBCs by electron microscopy demonstrates significant echinocytosis when they are compared to normal cells. Electrophoretic separation of the hemoglobin from T-RBCs shows a pattern different from normal cells and consistent with the pattern described for hemoglobin from spleen and bone marrow. The findings are consistent with bone marrow inadequacy and an increased splenic erythropoiesis which is insufficient to maintain normal hematological values. The hypothesis is presented that the RBCs synthesized under these circumstances appear in the circulation with an "immature" hemoglobin pattern and are hemolyzed more readily. This process then contributes to the hemolytic component and development of the anemia.