The Effects of Repeated. Doses of Bacterial Endotoxin on Erythropoiesis in the Normal and Splenectomized Mouse

Summary: A study has been made of the effects of repeated doses of bacterial endotoxin on erythropoiesis in the mouse. It was found that, in the intact mouse, 10 μg/day of Lipopolysaccharide B from S. abortus equi caused a fall in haemoglobin level, reticulocytosis, a severe reduction in bone‐marrow erythropoiesis, and an increase in splenic erythropoiesis. In the splenectomized mouse a fall in haemoglobin occurred but it was not accompanied by reticulocytosis, and the reduction in bone‐marrow erythropoiesis was much less marked. There was no great increase in red‐cell production over a. period of 20 days in the intact mouse and a raised percentage of 59 Fe into circulating blood at 10 days was due mainly to a raised percentage of iron‐incorporating cells in peripheral blood rather than a change in production rate. Random destruction of circulating red cells was not significantly increased in endotoxin‐treated animals. Bone‐marrow erythropoiesis remained depressed throughout 20 days of endotoxin administration. Possible mechanisms for such a shift of erythropoiesis, maintained over a considerable period, are discussed.