Glycobiochemical characterization of salivary carcinoembryonic antigen

Purpose: Carcinoembryonic antigen (CEA) is a highly glycosylated molecule, expressed in both normal and pathological conditions. This study was aimed at isolation and glycobiochemical characterization of human salivary CEA, and comparison of its structural properties with those of cancer-derived CEA. Materials and methods: CEA was isolated by immunoaffinity chromatography on an anti-CEA IgG-Sepharose 4B column. The isolated antigen was characterized by SDS-PAGE, gel filtration on Sepharose 4B and lectin-affinity chromatography using a panel of 6 plant lectins. Results: The isolated salivary CEA had a molecular mass of 180 kD and retained its structural and antigenic properties. Lectin-affinity chromatography indicated pronounced microheterogeneity of both salivary and cancer-derived CEA. Comparison of the lectin-binding patterns demonstrated lower relative amounts of distinct Phaseolus vulgaris agglutinin-reactive and Pisum sativum agglutinin-reactive glycoforms in salivary CEA than in cancer-derived CEA. Conclusion: The observed microheterogeneity of salivary CEA could have both functional and clinical relevance in relation to normal as well as to pathological oral physiology.