Soluble receptors released during acute pancreatitis interfere with the detection of tumor necrosis factor-α

Objective: To evaluate the interfering effect of tumor necrosis factor-alpha soluble receptor when measuring circulating concentrations of tumor necrosis factor-alpha in an experimental model of acute pancreatitis. Design: Randomized, controlled trial. Setting: Experimental laboratory. Subjects: Male Wistar rats. Interventions: Acute pancreatitis was induced by intraductal administration of 5% sodium taurocholate. Saline was administered in a control group. Serums were overloaded with known amounts of tumor necrosis factor-alpha or macrophage inflammatory protein-2. Measurements and Main Results: Three hours after induction, serum concentrations of free tumor necrosis factor-alpha, total tumor necrosis factor-alpha, and soluble receptor of tumor necrosis factor-alpha were measured. No detectable concentrations of free tumor necrosis factor-alpha were found in any experimental group. By contrast, significant increases in total tumor necrosis factor-alpha and soluble receptor of tumor necrosis factor-alpha were found after induction of pancreatitis. Overloading of serum with tumor necrosis factor-alpha resulted in detection of 50% of the expected concentrations of free tumor necrosis factor-alpha from control animals and only of 5% from the pancreatitis group. Overloading the serum with macrophage inflammatory protein-2 resulted in a detection of 100% of the expected concentrations in both control and treated animals. Conclusion: Circulating soluble receptor of tumor necrosis factor-alpha could interfere with the detection of tumor necrosis factor-alpha in some pathologies, such as pancreatitis, that are associated with increases in soluble receptor of tumor necrosis factor-alpha.