AFP isoforms and their clinical significance (overview).

AFP has maintained great clinical relevance as target tumor marker of germ cell tumors (YST = yolk sac tumors) and hepatocellular cancer (HCC) besides its occasional elevation in other malignancies. Its organ and tumor specificity is further limited by elevation in benign liver diseases (BLD) and in pregnancy. The binding of various lectins to its carbohydrate chain (5%) in addition to mere isoelectric focussing has been successfully used in the differentiation of AFP source and disease. The primarily used lectins in affinity electrophoresis and chromatography are Concanavalin A and lens culinaris agglutinin (LCA). The inclusion of other lectins (e.g. erythroagglutinating E-PHA, allomyrina dich. aggl. A lectin) and a more practical nomenclature have been used for characterization of 4 reactive patterns of cord serum/liver/BLD, HCC, g.i. tumor and YST type. In particular, data are reviewed concerning the clinically important liver AFP differentiation by means of LCA and E-PHA differentiation. In conclusion the investigation of AFP lectin binding in cases unexplained AFP elevation may be helpful in the differentiation of AFP source and malignancy.