The principle of the double antibody sandwich ELISA is represented in Figure 1. In this assay the Serum Amyloid A present in samples reacts with the anti-Serum Amyloid A antibodies which have been adsorbed to the surface of polystyrene microtitre wells. After the removal of unbound proteins by washing, the Detection Antibody and the HRP-Streptavidin conjugated with horseradish peroxidase (HRP) are added. These enzyme-labeled antibodies form complexes with the previously bound SAA.