The described Calprotectin (MRP 8/14) Stool (1 h) ELISA is intended for the quantitative determination of calprotectin (MRP (8/14, S100A8/A9) in stool. This ELISA is designed for the quantitative determination of calprotectin. The assay utilizes the two-site ``sandwich'' technique with two selected monoclonal anti bodies that bind to human calprotectin. Standards, controls and diluted patient samples which are assayed for human calprotectin are added to wells of microplate coated with a high affine monoclonal anti-human Calprotectin antibody. During the first incubation step, calprotectin in the samples is bound by the immobilized antibody. Then a peroxidase labelled conjugate is added to each well and the following complex is formed: capture antibody - human calprotectin - peroxidase conjugate. Tetramethylbenzidine (TMB) is used as a substrate for peroxidase. Finally, an acidic stop solution is added to terminate the reaction. The color changes from blue to yellow. The intensity of the yellow color is directly proportional to the Calprotectin concentration of sample. A dose response curve of the absorbance unit (optical density, OD at 450 nm) vs. concentration is generated, using the values obtained from the standard. Calprotectin, present in the patient samples, is determined directly from this curve.