Activation of Endotoxin-Induced Intravascular Coagulation in Congenitally C6-Deflcient Rabbits

Abstract

Activation of endotoxin-induced coagulation is thought to be caused by platelet factor 3. Since the release of platelet factor 3 after mixing platelets and endotoxin is dependent on the presence of complement factors, studies were performed in rabbits congenitally deficient in the sixth component of complement (C6). Endotoxin infusion (40 μg/kg × hr) caused a decrease in platelet counts in C6-deficient as well as in normal rabbits. Furthermore, after endotoxin infusion activation of intravascular coagulation occurred in C6-deficient rabbits to the same degree as in normal rabbits : prothrombin time and partial thromboplastin time were prolonged, factor V- and factor VII-activities were decreased, and ethanol gelation tests revealed positive results. Nine out of 10 C6-deficient rabbits demonstrated fibrin-rich microdots in the glomerular capillaries. Since platelet factor 3 is not released by endotoxin in the C6-deficient rabbits, these experiments make it likely that the release of platelet factor 3 does not represent the trigger mechanism of endotoxin-induced intra-vascular coagulation.(Supported by the Deutsche Forschungsgemeinschaft, Bad Godesberg, Germany.)