[Glycosphingolipids as tumor markers]

Interest in research in the sphere of tumours has concentrated for many years on finding tumour specific antigenic structures which can be used in immunodiagnosis and immunotherapy. During the last 30 years a number of monoclonal antibodies against tumours was prepared by means of which evidence was provided that antigens associated with tumourous processes have very often the nature of carbohydrates, in particular those linked to lipids, i.e. glycolipids. Carbohydrate structures with which anti-tumour antibodies react are usually found (at least in small concentrations) also in normal tissues. In the strict sense, from the chemical aspect specific tumour antigens do not exist but rather antigens associated with the tumourous process-tumour markers. Factors which influence the presence of a glycolipid of a tumour marker may be a) a simplification of the glycolipid spectrum by incomplete biosynthesis with concurrent deficiency of higher complex glycolipids and cumulation of the glycolipid precursor, b) activation of new pathways of biosynthesis, c) changes in the ceramide portion, d) lactonisation in the carbohydrate portion of the molecule, e) changes in the accessibility of the glycolipid molecule, their conformation and density on the cell surface. The author reviews the main glycolipid tumour markers which can be used in immunodiagnostics.