Prevention of Toxic Effects of Injected Thromboplastin by “Thromboplastinase”. ∗

Abstract

Summary

1. Loss of potency of tissue thromboplastic suspensions due to “thrombo-plastinase” action results in a concomitant loss of toxicity. Loss of potency by boiling does not alter the toxicity of thromboplastin. It would appear that the lipid moiety of thromboplastin may be essential for the production of toxic reactions. 2. Prior intravenous injection of “thromboplastinase” into rabbits protected the animals against the otherwise morbid or lethal effects of subsequent injections of a minimal toxic dose of thromboplastin. Heat-inactivated “thromboplastinase’ did not induce this protection. 3. Active “thromboplastinase”, in doses up to 10 times that needed for protection, was observed to cause no untoward reactions in the animals. 4. The mechanism of the protective effect in vivo, seems to be different from the in vitro destruction of thromboplastin by “thromboplastinase”. The nature of this effect is presently under investigation.