ELISA is based on the solidization of antigens or antibodies and enzyme markers of antigens or antibodies. Antigens or antibodies bound to the surface of the solid-phase carrier still maintain their immunological activity, and enzyme-labeled antigens or antibodies retain both their immunological activity and enzyme activity. During determination, the specimen under examination (the antibody or antigen in it) reacts with the antigen or antibody on the surface of the solid-phase carrier. The antigen antibody complex formed on the solid-phase carrier is separated from other substances in the liquid by washing method. The antigen or antibody, which is then added with enzyme markers, is also combined in the solid phase vector by reaction. At this time, the amount of enzymeon on the solid phase is proportional to the amount of the substance under examination in the specimen. After adding the substrate of the enzyme reaction, the substrate is catalyzed by the enzyme as a colored product, the quantity of the product is directly related to the amount of the substance under examination in the specimen, so it can be qualitativeor or quantitative analysis according to the color depth. Because of the high catalytic efficiency of the enzyme, the results of the immune response are indirectly magnified, which makes the measurement method highly sensitive.
ELISA can be used to determine antigens, as well as antibodies. However, there are many factors affecting the results of the Elisa experiment, so strengthening the quality assurance of each link can give full play to its methodological advantages.