As to the relative contribution of individual cytokines, neutralization studies with specific antibodies would suggest a major role of endogenous IL-6 and, to a lesser extent, of IL-1.40 Although TNF can activate coagulation when injected in animals or in man and can induce TF in vitro, endogenous TNF does not appear to play a significant role in activation of coagulation during endotoxemia or gram-negative sepsis. This evidence concerns the gene TF and serum lipopolysaccharide activity.