PHA-E_4 レクチンによる血清α-フェトプロテインの分画分析 : 小児腫瘍診断における意義

抄録

Lectins can recognize the differences of sugar chains in glycoproteins. The sugar chain of a-fetoprotein (AFP) is known to have organ specificity and also tumor specificity. Subfractionation analysis of serum AFP by crossed immuno-affino-electrophoresis using Phytohemagglutinin-E_4 (PHA-E_4) lectin was carried out in 20 AFP-producing tumors in childhood and 10 adult carcinomas. AFPs in cord blood and infantile obstructive liver diseases were also analyzed with the same method. PHA-E_4 lectin can clearly separate serum AFP in 5 subfractions, i. e., tightly bound (TB) , loosely bound (LB 1 , LB 2 , LB 3) and unbound (UB) fractions. With this analysis, serum AFP could clearly be classified as the liver type and the yolk sac tumor type. The liver type could further be subdivided into fetal liver type and malignant liver tumor type. AFP in gastric cancer and pancreatic cancer as well as yolk sac tumor were the yolk sac tumor type. This analysis also disclosed that the recognition sites of sugars in AFP by PHA-E_4 and Lens culinaris agglutinin (LCA) were completely independent. This new method for glycosylation analysis of AFP is particularly useful in determining the origin of tumor and in early detection of hepatoma at risk in patients with liver cirrhosis.