As a sensitive, specific, convenient and rapid immunoassay method, ELISA has been successfully applied in detection of various antibodies and antigens. The detected antibody is used to evaluate organism immunity qualitatively or quantitatively in the first place; and then, it serves as an important diagnostic detection index. In terms of the detected antigen, it is used to:
(1) test various microorganisms and their macromolecular products (e.g., infectious disease diagnosis; microorganism classification and determination; and, research on bacterin and vaccine);
(2) test various macormolecular substances within organisms, such as different serum proteins, soluble blood-group substances, polypeptide hormones, cytokines and biomarkers that all can be detected as antigens;
(3) test cell-surface molecules, including various differentiation antigens (e.g., CD antigen) on a cell surface and allotypic antigens (e.g., blood group antigens or MHC antigens); and
(4) test haptens, such as drug residues, additives and toxin that all belong to micro-molecular haptens.