Sequential study of serum glycoprotein fucosylation in acute hepatitis

Background: α-Fetoprotein is a useful diagnostic marker in hepatocellular carcinoma, during which its serum level increases and its glycan structure is hyperfucosylated. Normally-expressed glycoproteins (α1-antitrypsin and transferrin) are also hyperfucosylated in hepatocellular carcinoma. α-fetoprotein serum levels are also increased in conditions associated with hepatic regeneration, such as acute hepatitis. We conducted a longitudinal study of the α1–6 fucosylation pattern of serum α-fetoprotein in ten patients with acute hepatitis and compared it to that of transferrin and α1-antitrypsin. Methods: Protein levels were measured by using immunochemical assays. Crossed affinoimmunoelectrophoresis in the presence of Lens culinaris agglutinin was performed for each protein, and the fucosylation index, corresponding to the agglutinin reactive fraction, was determined. The results were compared to those in 25 healthy donors and five newborns. Results: α-Fetoprotein was hyperfucosylated and remained stable throughout the course of the disease. In contrast, serum transferrin and α1-antitrypsin gradually became hyperfucosylated during the course of acute hepatitis. The transferrin and α1-antitrypsin fucosylation indexes correlated with each other, but not with the α-fetoprotein fucosylation index. No correlation was found between α-fetoprotein, α1-antitrypsin and transferrin fucosylation indexes and the corresponding glycoprotein serum levels. Conclusions: Hyperfucosylation of α-fetoprotein is not specific to hepatocellular carcinoma. Increased α1–6 fucosylation should not be considered solely as a tumour marker, but might also reflect cell proliferation. The study of α1–6 hyperfucosyation process of normally-expressed glycoproteins awaits further investigation, to test its usefulness as a new marker of liver regeneration during the follow-up of acute hepatitis.