Abstract
The lectin-binding properties (such as Concanavalin A (Con A)) of serum alpha-feto-protein (AFP) are very useful in the differentiation of yolk sac-type AFP from hepatictype AFP. Con A can bind with 50-70% of the serum AFP derived from yolk sac tumor, while Con A can bind with about 90% of the serum AFP derived from hepatocellular carcinoma (HCC). Ten yolk sac tumors (YSTs) and HCCs were examined immunohistochemically in order to differentiate yolk sac-type AFP from hepatic-type AFP. Formalinfixed, paraffin-embedded serial sections were stained by the peroxidase-antiperoxidase (PAP) method for AFP (PAP-AFP) and paradoxical Con A (P-Con A), which has been reported to detect glycoprotein including AFP. Observation were conducted to determine whether the distribution of AFP paralleled that of Con A positivity. AFP was negative for the P-Con A staining in all 10 YSTs. On the other hand, AFP was strongly positive for the same staining in all HCCs. A similar staining pattern for AFP was observed in yolk sac-endodermal cells and embryonal hepatocytes. It was suggested that the PAP-AFP and P-Con A staining might facilitate the histological differentiation of yolk sac-type AFP from hepatic-type AFP, and that it would be very useful for clarifying the histogenesis of various AFP-secreting tumors.
