A simplified solid-phase radioimmunoassay for carcinoembryonic antigen

A simple and rapid solid-phase radioimmunoassay for the measurement of carcinoembryonic antigen (CEA) levels in sera or plasma is described. The procedure involves perchloric acid (PCA) extraction of the samples, followed by a rapid neutralization of excess acid with alkaline buffer solution. The PCA extracts are assayed uing antibody-coated plastic tubes and radio-labeled anti-CEA antibody as a marker. The assay may be completed in one day. The solid-phase direct-binding assay demonstrated a sensitivity of 0.5 ng CEA/ml plasmin and a marked tolerance to variations in pH and ionic strength of the system. A fair correlation between the CEA levels determined by the solid-phase radioimmunoassay and zirconium phosphate gel method was observed.