The haematopoietic response to burning: studies in an animal model.

Changes in haematopoiesis which occur in humans after burning injury may have important effects on morbidity and mortality. Because of the heterogeneity of burn patients we studied the regulation of blood cell formation which occurs in an animal using an established mouse model. Mice received a 20 per cent third degree scald injury on the back. Serial studies of a variety of haematopoietic parameters including stem cell, bone marrow and peripheral blood findings were done post burn. Although anaemia occurred frequently after injury red blood cell survival studies and examination of the stool for occult blood showed that neither haemolysis nor blood loss were primary causes of the anaemia. Bone marrow erythroid stem cells fell markedly post burn and this was associated with the development of a substance in serum capable of inhibiting red cell colony formation but not white cell colony formation of normal marrow cells. Reticulocytosis occurred but was mild and the anaemia was primarily of the aregenerative type. Partial compensation for the depressed marrow erythropoiesis occurred in the spleen with an increase in erythroid colony-forming cells and erythroblasts. Marked granulocytosis occurred in the peripheral blood and bone marrow. There was an increase in splenic granulocytic stem cells post burn. Megakaryocytosis was striking in the bone marrow and spleen and there was an increase in peripheral blood platelet count. Evidence of immune stimulation included an increase in the size of the spleen and an increase in peripheral blood and splenic lymphocytes. Correlations of many of these findings suggested that the events were not occurring at random but that the changes in haematopoiesis were linked together. We speculate that the anaemia was the result of the increase in granulopoietic and thrombopoietic effort seen post burn.