Immunological and chemical studies on sub-fractions of carcinoembryonic antigen.

Abstract The results of this study have shown that carcinoembryonic antigen (CEA) and also its desialylated product can be separated by con A affinity chromatography into three immunologically related sub-fractions. Each fraction reacted with established anti-CEA antisera (anti-A) and also with antisera specific for a determinant, common to both CEA and a normal glycoprotein NGP. Carbohydrate analysis and circular dichroism studies have revealed chemical differences between the fractions. Removal of sialic acid from CEA appears to have no effect on its binding to either antibody or concanavalin A and the presence of the latter, up to a 40-fold excess, does not inhibit the binding of CEA to antibody.