Effect of interleukin-6 blockade on tissue factor-induced coagulation in human endotoxemia.

Objective: Clinical trials show that interleukin (IL)-6 represents a predictive marker in human sepsis. Furthermore, IL-6 has been proposed as a candidate mediator for endotoxin (lipopolysaccharide)-induced coagulation activation: In a primate model, an αIL-6 antibody (αIL-6 Ab) almost abolished lipopolysaccharide-induced coagulation activation. Therefore, we wished to determine if an αIL-6 Ab (B-E8) may also attenuate lipopolysaccharide-induced activation of coagulation in humans. Design: The study was a randomized, double blind, placebo-controlled parallel group trial (n = 12 per group). Setting: University medical center. Patients: Healthy volunteers. Interventions: Healthy volunteers were randomized to receive either 80 mg of a monoclonal anti-IL-6 Ab (B-E8) or placebo intravenously before bolus infusion of 2 ng/kg lipopolysaccharide. Measurements and Main Results: B-E8 effectively decreased IL-6 bioactivity as measured by a B9-bioassay in vitro and concentrations of C reactive protein. However, B-E8 did not decrease lipopolysaccharide-induced tissue factor-messenger RNA transcription or plasma concentrations of downstream coagulation variables (prothrombin fragment 1 + 2, thrombin-antithrombin III complexes, and D-dimer concentrations). Similarly, tumor necrosis factor-α concentrations, fibrinolytic activity (plasmin-antiplasmin complexes), endothelial activation (soluble E-selectin), and IL-10 were unaffected. Conclusion: IL-6 does not appear to mediate early-phase lipopolysaccharide-induced coagulation activation in humans.