Measurement of Insulin Immunoreactivity in Human Plasma and Serum

Featured article: Andersen L, Dinesen B, Jorgensen PN, Poulsen F, Roder ME. Enzyme immunoassay for intact human insulin in serum or plasma. Clin Chem 1993;39:578–82.1 Our 1993 report described a monoclonal antibody–based ELISA for insulin that had greater specificity than existing RIAs. This specificity allowed determination of intact insulin only, without comeasurement of proinsulin and the conversion intermediate des(31,32)-proinsulin. In patients with type 2 diabetes or with high concentrations of insulin precursors in the blood, the assay measured intact insulin immunoreactivity from plasma and serum samples. The assay was also suitable for large-scale studies. Immunochemical methods for estimating insulin concentrations have been used for 50 years. In 1959 Berson and Yalow introduced the RIA method for the determination of insulin (1), which led to a Nobel Prize in 1977. Competitive insulin RIAs based on polyclonal antibodies had many limitations, however, including limited stability of the radioactive isotope, limited amounts of the antibodies, and unspecific determination of insulin precursors and insulin degradation products together with insulin. The assays were laborious for large-scale use. The discovery of monoclonal antibodies made it possible to produce potentially unlimited amounts of …