Procoagulant protein levels are differentially increased during human endotoxemia

On the basis of plasma interleukin levels it was suggested that there is an inflammatory component to the risk of venous thrombotic disease. Other evidence shows that elevated levels of coagulation factor (F)VIII, FIX, FX and FXI are risk indicators for venous thrombosis, but the reasons for elevation remain unclear. We tested the hypothesis that the elevated levels could reflect an inflammatory reaction by measuring coagulation factor levels during experimental human endotoxemia. Male volunteers received endotoxin (4 ng kg-1), and blood samples were obtained before and at multiple time points after the challenge. Plasma was used for a panel of coagulation tests. Antigen levels of FVIII, von Willebrand factor (VWF), FIX, and FX were increased after endotoxin administration, reaching peak levels between 2 and 5 h. Within 24 h levels normalized, except for FVIII and VWF levels that remained at > 200%. Fibrinogen levels, and to a lesser extent FXI levels, also responded with an increase, but slower. These levels did not return to normal during the observation period. FVII levels were strongly depressed. FVIII, FIX and FX reacted immediately and strongly to endotoxin administration. The time pattern of this response is different from the slower so-called acute phase response, which appeared to be followed by FXI and fibrinogen. These increased levels of coagulation factors during an inflammatory state provide new ways of explaining why elevated levels of FVIII, FIX and FXI behave as risk indicators disease.