Development of a Radioimmunoassay for Gastrin

Early studies on the physiology of gastrin were dependent upon the observed secretory response, but direct measurement has been made possible by the recent development of a radioimmunoassay by McGuigan.1Because gastrin has functional and structural similarities with pancreozymin-cholecystokinin (PZ-CCK), with synthetic pentagastrin, and with caerulein,2it is desirable that an assay be highly specific for gastrin. In this report we describe the development of a specific radioimmunoassay in which the antibodies were made with unconjugated gastrin used as an antigen. The antibodies have proved to be specific for gastrin and show only minimal cross-reaction with related substances. Gastrin has been measured in antral extracts and the serum and tumor extracts of patients with the Zollinger-Ellison syndrome. Materials and Methods Antibodies were prepared by immunizing with hog gastrin and synthetic human gastrin 1. The hog gastrin was prepared in this laboratory by the method of Gregory and Tracy.