enzyme-linked immunosorbent assay (ELISA), a laboratory technique for detecting specific antigens or antibodies by using enzyme-labeled immunoreactants and a solid-phase binding support, such as a test tube. A number of different enzymes can be used, including carbonic anhydrase, glucose oxidase, and alkaline phosphatase. Labeling is done by covalently binding the enzyme to the test substance through an enzyme-protein coupling agent such as glutaraldehyde. Products of the reaction may be detected by fluorometry or photometry. ELISA is nearly as sensitive as radioimmunoassay and more sensitive than complement fixation, agglutination, and other techniques.
