Interference of soluble TNF-α receptors in immunological detection of tumor necrosis factor-α

Abstract

We have studied the interference of soluble rumor necrosis factor-α receptor p55 (sTNF-R55) on the quantification of rumor necrosis factor-α (TNF-α) in three immunoassays: the commercially available enzyme amplified- sensitivity immunoassay (EASIA) of Medgenix and the ELISA of Boehringer Mannheim, and an assay based on electrochemiluminescence (ECL) technology. TNF-α measurements by EASIA and ELISA were not affected by the presence of sTNF-R55, but results by the ECL method were clearly influenced by the receptor. We then performed a second set of experiments with the ECL system to examine what factors might influence the importance of interference from sTNF-R55 and soluble TNF-α receptor p75 (sTNF-R75), which influences TNF-α measurements the same as sTNF-R55. We found that extending the incubation time and increasing the concentration of capture antibody decreased the interfering capacity of sTNF-R55 and sTNF-R75. A clear insight into these phenomena is of utmost importance for correct interpretation of cytokine quantification.