Isolation and immunochemical and chemical characterization of carcinoembryonic antigen-like substances in colon lavages of healthy individuals.

Material with carcinoembryonic antigen (CEA)-like activity, isolated from colon lavages of healthy individuals, has been chemically characterized. The CEA-like activity in these lavages was purified by gel filtration on Sepharose 6B and Sephadex G-200 and by affinity chromatography on concanavalin A linked to Sepharose. The purified material migrated in polyacrylamide-sodium dodecyl sulfate electrophoresis as a single diffuse band with mobility identical with that of tumor CEA. The material with CEA activity from tumor tissue and from normal colon lavages gave lines of identity in double diffusion experiments and had similar inhibition curves with esssentially the same specific activities in a radioimmune assay for tumor CEA. The amino acid and carbohydrate compositions were similar to that observed for CEA tumor preparations. Lysine was the single amino terminus. Methylation analysis demonstrated that the monosaccharide linkages were similar to those in CEA isolated from tumor tissue.