Hemolytic Anemia in Rabbits Following Injection of Bacterial Endotoxin

Abstract

Summary

1. A mild hemolytic anemia secondary to intravenous injection of bacterial endotoxin into rabbits is described. The anemia is characterized by reticulocytosis, decreased hemoglobin levels in the blood, and decreased survival of red blood cells. 2. Single injections of endotoxin occasionally produce a mild hemolytic response in rabbits during second week after injection. Repeated injections of endotoxin lead to more striking hemolytic changes which also reach their peak during second week after first injection. The hemolytic process tends to abate despite repeated administration of endotoxin. 3. Evidence is presented to indicate that the hemolytic response is not due to demonstrable changes in the red cells of the animals receiving endotoxin. There is no change in osmotic or mechanical fragility of the red cells, no sensitization to appropriate anti-rabbit-protein antisera or to polyvinyl pyrrolidone, and no evidence of hemagglutination in vivo during the hemolytic episode. In addition, there is no decrease in the life span of red cells when these are taken from an anemic rabbit and transfused into a normal one. 4. Presence of antibody does not seem to play a critical role in development of hemolytic anemia, and the presence of the spleen is not essential for the hemolytic response to endotoxin. 5. It is suggested that the hemolytic response is most likely due to an as yet unexplained activation of the reticulo-endothelial system.