PREPARATION AND EVALUATION OF ACTH ANTIBODIES

Abstract

ABSTRACT A method for rapid screening of ACTH antibodies has been developed. It consists of a simplified study of the modification of the antigen-antibody equilibrium by adding standard ACTH. Different immunization methods have been studied according to the type of antigen and its preparation, the rhythm of injections as well as the amount of ACTH injected. Among these different methods, using 267 guinea pigs, only the injection of 25 guinea pigs with 30 IU of human ACTH adsorbed on 5 mg of vegetal charcoal made it possible to obtain 7 antibodies suitable for a specific and sensitive radioimmunoassay of ACTH in human plasma without previous extraction. These antibodies react with the portion 17–24 of the ACTH molecule, and their equilibrium constants are distributed from 2.1011 m−1 to 1.1012 m−1. Assays performed with one of these antibodies in the plasma of normal subjects and of patients suffering from adrenal-pituitary axis disorders are essentially identical with the values obtained by bioassay and are in good agreement with the results of radioimmunoassay performed by other investigators.