T. T. Ngo and H. M. Lenhoff Department of Developmental and Cell Biology University of California, Irvine, CA 92717 In 1959, Yalow and Berson used insulin labeled with radioactive iodine to develop a quantitative immunological method for determining the amount of insulin in human plasma. Their method depends upon competition between insulin labeled with radioactive iodine (II 1) and unlabeled insulin from plasma for a fixed and limited number of specific binding sites on the antibody to insulin. The amount of the labeled insulin bound to the antibody is inversely proportional to the amount of...

The basis of all immunoassays is the interaction of antibodies with antigens. The most widely used immunoassay technique is radioimmunoassay (RIA) which was first developed by Yalow and Berson in 1959. The principle of RIA is elegantly simple. It utilizes a competitve binding reaction between analytes and a radio-labeled analog of the analytes (the tracer) for anti-analyte antibodies. In addition to its exquisite specificity, extraordinary sensitivity, good accuracy and precision, ease and rapidity of assay and simplicity of assay development, the applicability of RIA to a wide variety of...