Some Effects of Escherichia Coli Endotoxin on the Graft-Versus-Host Reaction in Mice

Endotoxin derived from Escherichia coli given to Ft hybrid mice 4 days after injection of parental spleen but not thymus cell potentiated graft-versus-host (GVH)-dependent splenomegaly. This potentiation was observed 21 days after injection of parental spleno-cytes. The effect was strongly time-dependent, as it was present only when endotoxin was injected 4 days after the injection of cells. Administration of mouse antiendotoxin serum before endotoxin did not change this effect. In sublethally irradiated animals undergoing GVH reactions the administration of endotoxin 4 days after the injection of cells resulted in significant exacerbation of disease and increased mortality.