An Overview Regarding the History of Immunoassays

In 1950, Dr. Solomon Berson and Dr. Rosalyn Yalow conducted investigative studies regarding insulin metabolism in diabetic patients at the Bronx veterans Administration Hospital. They found out that globulins which bind to insulin in the patients who were insulin-treated were actually antibodies.

When these antibodies were studied under the effect of radio labeled iodine, it was found that they body generates these antibodies while responding to small proteins. Even though the esteemed journals of that time, the ‘Science’ along with the ‘Journal of Clinical investigation’ rejected this theory, the researchers still produced an immunoassay to measure the concentration of insulin. Their discovery was termed as RIA – Radioimmunoassay. The works of Rosalyn S. Yalow deemed her to co-win a Nobel Prize in Medicine/Physiology in 1977. She was the first American Doctor to win this award.

After Yalow and Berson published their research, they applied this technology to the field of endocrinology and discovered many assays for ACTH –Adenocorticotrophic Hormone, growth hormone, PTH – ParaThyroid Hormone, and other different hormones. Yalow had never regretted not patenting RIA. This was so because she believed that patents keep things away from other people as their purpose is to make money. Yalow wanted that others should also be able to use RIA which is why; she never patented the RIA research.

After RIA, many laboratories used radioisotopes in the labeling of antibodies and antigens. However, due to this, concerned were raised as to the safety of laboratory technicians, equipment expense while using the technology and the discarding of radioactive waste. Later researches were introduced which utilized the input of alternative labels such as nontraditional labels and non radio isotopic labels in immunoassay development. The EIA – Enzyme Immunoassay and ELISA – Enzyme Linked Immunoassay were developed by Perlmann and Engvall in 1971 in Sweden and in Netherlands by van Weeman and Schuurs respectively. These tests incorporated the use of enzymes in place of radioisotopes to detect the presence of substances in blood. The earlier versions of these tests were not as precise and sensitive as the RIA, but over the time, these were utilized and further developed by automation process and further assay enhancements.

In the 1970s, the development of EMIT – Enzyme Multiplied Immunoassay Technique led to further development of enzyme related immunoassays by Syva Company. Originally, this technique was established in 1966 in a joint venture of Varian and Syntex corporations. Emit was officially released in 1972 with a corporate name of Syva. This homogenous enzyme assay was automated, didn’t require separation and utilized spectrophotometers which are easily available in the market.

Syva immunoassays which were commercially produced first were developed to be used in the methadone maintenance treatment programs. When the US military explored methods to curb the drug addiction problem in troops from Vietman, further development in drug testing emerged and expanded. Drug testing further became a routine especially when federal government, private employers and the US military incorporated the drug testing programs ubiquitously. Major developments in homogenous immunoassays have been due to the development of illicit drug testing and therapeutic drug testing programs

The development of other techniques such as FPIA – Fluorescence Polarization Immunoassay, KIMS – Kinetic Interaction of Particles and CEDIA – Cloned Enzymes Donor Immunoassay have advanced the field of homogenous assays. Many EIA alternative formats are also available with commercial kits which involve the techniques of lateral flow technology and chemo luminescence microarrays. The lateral flow devices are easily available in different formats such as visual reading and instrumental reading which are now very much evolved as compared to the first assay device developed in 1979. The availability of automation gives the laboratories a choice to choose any type of reagent system they like.

In short, the development of immunoassays has taken place in many leaps and bounds after the introduction of RIA in 1959 by Berson and Yalow. These techniques are widely used in many aspects of clinical laboratory. The immunoassay system has greatly improved diagnostic and medical research methods. Being commercially available now, it is easy to use and the automation processes have enabled it to be used as a standard practice in many drug testing and laboratory testing systems.

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