Isolation of anti-carcinoembryonic antigen (CEA), specific immunoglobulins and their use in immunocytochemical and enzyme-immunoassays (ELISA)

Anti-carcinoembryonic (CEA) polyclonal antibodies in sheep and rabbits were raised using purified CEA from acid extracts of human colon adenocarcinoma. CEA was purified by gel filtration on Sepharose 4B CL and chromatography on DEAE-Sephadex A50. The antiserum was adsorbed with human serum and perchloric acid extract from normal colon. Anti-CEA IgG was purified from monospecific antiserum by ion-exchange chromatography and its specificity was tested on cryostat sections from colon adenocarcinoma by the indirect immunoperoxidase technique. The specific reaction was compared with that obtained by using a similar technique and two CEA specific monoclonal antibodies. An anti-CEA IgG peroxidase conjugate was obtained allowing to establish a "sandwich" ELISA-CEA system with two antibodies. CEA determinations were made in a group of 15 normal controls (mean value 4.8 +/- 0.4 ng/ml) and in 30 colorectal tumor patients (mean value 26.6 +/- 2.15 ng/ml). The anti-CEA antibodies are proven useful in immunocytochemical and ELISA techniques and may be further used in radioimaging of tumors.