Escherichia coli bacteremia in the squirrel monkey. I. Effect of cobra venom factor treatment.

Squirrel monkeys were significantly depleted of complement by a nontoxic protein constituent of cobra venom, and the influence of cobra factor (CoF) treatment on the course of Escherichia coli bacteremia was studied. Striking neutropenia occurred rapidly in control animals while the rate of occurrence of neutropenia was 20 to 30 times slower in the CoF-treated animals, suggesting that the E. coli-induced neutropenia was at least partially a complement-mediated response. In the CoF-treated monkeys, the initial rate of clearance of the E. coli from the circulation tended to be slower and the resultant levels of bacteremia were higher than in control animals. These observations are consistent with a hypothesis that complement-mediated neutrophilic leucocyte function is an important host defense mechanism in gram-ngeative bacillary bacteremia.