ABSTRACT
The introduction of the immunoassay revolutionized the determination of biologi cally active substances such as hormones, drugs, and enzymes. One example, which made an indelible impression in the author’s mind, was the determination of insulin by radioimmunoassay. Previously, insulin was measured by a bioassay which required the induction of a diabetic coma in rats. Several animals were needed at each of several concentrations of hormone in order to achieve acceptable precision. In contrast, the radioimmunoassay is precise, rapid, and does not require the use of laboratory animals once the antisera are available. Another example, more widely appreciated, is the im munological determination of the pregnancy-associated hormone HCG. This forms the basis of rapid, reliable, and easy test kits, some of which can be used at home. Before the development of immunoassays, pregnancy testing depended on the induction of ovulation in laboratory animals.
