Development of an antibody-lectin enzyme immunoassay for fucosylated α-fetoprotein ☆

Abstract Background Fucosylation is one of the most important types of glycosylations related to cancer. Our previous studies of the enzymatic basis and structural studies of α-fetoprotein (AFP) samples from liver cancer patients indicated that core-fucosylation by α1,6-fucosyltransferase (FUT8) resulted in the production of fucosylated AFP, and in fact fucosylated AFP allowed differential diagnosis in some types of liver cancer from liver cirrhosis. This served as a predictive biomarker for the development of liver cancer 3 to 18 months before it could be detected using imaging techniques. Fucosylated AFP is currently measured by means of a liquid-phase binding assay (LBA) or by an electrokinetic analyte transport assay (EATA). However, these methods require special instrumentation that is currently available only in major medical laboratories. To overcome this problem, we attempted to develop an enzyme immunoassay (EIA) based on the sandwich technique with specific antibody and lectin. Results Dilute solutions of highly fucosylated AFP in human sera were assayed using a microtiter plate coated with a periodate-oxidized anti-AFP antibody, a fucose-specific biotinylated Aleuria aurantia lectin (AAL), a peroxidase-conjugated streptoavidin, and a chemiluminescent detection system. The technique was able to measure highly fucosylated AFP diluted to 5 to 80 ng/ml in human sera using the developed antibody-lectin EIA in combination with the enrichment of AFP. Conclusion A simple method using an antibody-lectin EIA for quantifying fucosylated AFP that does not require special instrumentation was developed. General significance The method can be generally applied to the quantitative measurement of various fucosylated glycoproteins using specific antibodies. This article is part of a Special Issue entitled Glycoproteomics.