Further link between complement activation and blood coagulation

EVIDENCE for interactions between the complement and haemostatic systems has come from two lines of research—blood platelets have been shown to interact with various complement components1–6, and more ambiguous results have been obtained with respect to the role of complement in endotoxin shock and the Shwartzman reaction7–13. We report here that the activated complement component C3b triggers a marked increase of tissue thromboplastin (factor III) activity in cultured human monocytes. Differential counting and nonspecific esterase staining14 of the final preparations regularly revealed more than 85% monocytes.