Thrombomodulin Release in Baboon Sepsis: Its Dependence on the Dose of Escherichia coli and the Presence of Tumor Necrosis Factor

This study was designed to test whether thrombomodulin is shed in septic baboons and whether shedding is blocked by antibody to tumor necrosis factor (anti-TNF). Live Escherichia coli were injected intravenously into 24 baboons according to one of the following regimens: 5 x 10(8) or 2 x 10(9) cfu/kg (n = 6/8), 2 x 10(9) cfu/kg with placebo (n = 5), or pretreatment with 1 mg/kg anti-TNF 2 h before E. coli injection (n = 5). E. coli administration resulted in a significant release of thrombomodulin in a dose-dependent manner; however, thrombomodulin release was significantly attenuated (180 to 40 ng/mL) by anti-TNF pretreatment. This is parallel to the reduction of neutrophil activation (elastase). These results provide evidence for an E. coli dose-related and TNF-dependent thrombomodulin release into the plasma of septic baboons and suggest a possible role of anti-TNF in protection of the endothelium.