1 - Past, present, and future of immunoassays

Abstract

This chapter deals with the past, present, and future of immunoassays. Immunoassays employ antibodies as analytical reagents. The assays are based on the observation that in a system containing the analyte and a specific antibody, the distribution of the analyte between the bound and free forms is quantitatively related to the total analyte concentration. Immunoassays were first introduced in the 1960s by Berson and Yalow for insulin and by Ekins for thyroxine. In the first immunoassays, the distribution of the analyte between the bound and free forms was monitored by adding a fixed known concentration of radioisotopically labeled analyte followed by separation of the bound and free analyte and measurement of the radioactivity the bound fraction. Immunoassay applications expanded to areas such as therapeutic drug monitoring, measurement of enzymes, tumor markers, lipoproteins, vitamins, and many other metabolites, and the detection and quantification of antibodies and antigens associated with infectious agents. Immunoassays with labeled antibodies were introduced and shortly afterward the first “two-site” immunoassays were described.