Modifications and evaluation of double antibody radioimmunoassay of human carcinoembryonic antigen.

Double antibody radioimmunoassay of carcinoembryonic antigen (CEA), a cancer-associated antigen of the human digestive system, was subjected to certain modifications and critically evaluated. Modifications pertained to: (a) the production of a high titer goat anti-CEA antiserum that was rendered highly specific by solid phase immunoabsorption with cyanogen bromide-activated Sepharose conjugates of normal plasma liver, and colon perchloric acid-soluble glycoprotein antigens: (b) the introduction of suitable alterations in the experimental conditions of radioiodination procedure to minimize and to prevent breakdown of the antigen, thus prolonging the storage of the labeled antigen; (c) the extended incubation period of CEA-anti-CEA immune reaction; and (d) the use of sodium acetate buffer, pH 6.1. Furthermore, the use of an automatic pipetting station for accurate and rapid reagent dispensation and statistical analysis of the radioimmunoassay data on a modern computer to ensure strict quality control of the assay provided some definite improvement over the existing assay.