IMPROVED ELISA IMMUNOASSAY FOR CALPROTECTIN

摘要

An improved immunoassay for S100A9 provides increased reproducibility and accuracy for the determination of calprotectin, allowing more accurate diagnosis and screening for inflammatory bowel disease. In particular, the immunoassay is a sandwich immunoassay that uses an unlabeled monoclonal anti-S100A9 antibody as the capture antibody and a labeled polyclonal anti-calprotectin antibody as the detection antibody. Further improvements in reproducibility and accuracy are obtained by using citrate buffer as a coating buffer to coat a solid support, such as used in an ELISA assay, with the capture antibody. In general, the method comprises the steps of: (1 ) providing a monoclonal anti-S100A9 antibody; (2) coating the monoclonal anti-S100A9 antibody onto a solid support; (c) reacting the solid support with coated monoclonal anti-S100A9 antibody with a sample that may contain calprotectin to bind any calprotectin in the sample to the solid support; (d) washing the solid support; (e) reacting the solid support with a labeled polyclonal anti-calprotectin antibody to bind the labeled polyclonal anti-calprotectin antibody to the calprotectin bound to the solid support, the labeled polyclonal antibody being able to produce a detectable signal proportional to the concentration of the antibody bound to the calprotectin bound to the solid support; and (f) measuring the detectable signal to determine the concentration of calprotectin in the sample. The invention further includes diagnostic methods, methods of screening antibodies, and kits.