A Rapid and Specific Method for Separation of Bound and Free Antigen in Radioimmunoassay Systems

Abstract

A method for increasing the speed of separation of bound and free antigen in radioimmunoassay systems with no loss in the specificity of binding is reported. The technique uses a mixture of 2nd antibody [Ab] and polyethylene glycol. It is not species or Ab specific, and systems using specific 1st Ab from rabbit, goat or sheep are all functional. Results for the assay of parathyrin, calcitonin and ACTH are described here, although the system works for triiodothyronine, thyroxine, thyrotropin, thyroxine binding globulin and transferrin. The time taken for the reaction between 1st and 2nd Ab is in the order of seconds, and the stability of the complex is unchanged over a period of hours.