Differentiation antigens of human germ cell tumours: distribution of carbohydrate epitopes on glycolipids and glycoproteins analyzed using PDMP, an inhibitor of glycolipid synthesis.

Human and mouse embryonal carcinoma (EC) cells are characterized by their expression of cell surface carbohydrate antigens, present in both glycolipids and glycoproteins. These antigens disappear upon differentiation and are replaced with other antigens. We have used the inhibitor of glucosyl ceramide synthetase, 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), to study the distribution of carbohydrate epitopes between glycolipids and glycoproteins. PDMP inhibited the expression of glycolipid antigens, but not glycoprotein antigens assayed by immunofluorescence and thin layer chromatography. In the case of SSEA1, we observed expression on both glycolipids and glycoproteins. Resistance to PDMP inhibition suggests that glycoproteins carry the immunodominant form of SSEA1 on the cell surface of differentiated human EC cells and undifferentiated murine EC cells.