Reduction of serum complement in rabbits after injection of endotoxin

Injection into rabbits of a consistently lethal dose of endotoxin regularly produced a rapid and sustained fall of complement levels and lowered the titers of antibody to endotoxin. Doses of endotoxin below the LD(50) lowered complement levels sporadically but not the titers of antibody to endotoxin. The possibility is discussed that complement may be involved in the mechanisms responsible for the lethal action of endotoxin.