Enzyme Immunoassay of Antibody

Abstract

The detection of specific antibodies in body fluids has proven to be of considerable value in diagnostic medicine for a wide variety of diseases, including those of infectious as well as of auto-immune origins. A number of divergent methods have been developed for these purposes, such as complement fixation, passive hemagglutination, viral hemagglutination inhibition, immunofluorescence and latex agglutination procedures. All of these require serial dilution titration for quantitation, which is tedious and reduces precision, and all suffer from the fact that the readings are largely subjective. Weak reactions are often very difficult to distinguish from negative ones. The development of enzyme immunoassays, particularly of the “sandwich” ELISA type (Engvall and Perlmann, 1972), permitted quantitative estimations to be made with a single dilution of serum or plasma over a wide range of values. They also easily permit antibody activity in the various immunoglobulin classes to be distinguished. The results are objectively read in a photometer, and the intensity of the reading is directly correlated with the antibody level. By use of the appropriate antigen in the solid phase and the correct type of enzyme-labeled anti-immunoglobulin conjugate, numerous antibody tests can be designed using the same format.