Sequential study of serum glycoprotein fucosylation in acute hepatitis.

BACKGROUND

alpha-Fetoprotein is a useful diagnostic marker in hepatocellular carcinoma, during which its serum level increases and its glycan structure is hyperfucosylated. Normally-expressed glycoproteins (alpha 1-antitrypsin and transferrin) are also hyperfucosylated in hepatocellular carcinoma. alpha-fetoprotein serum levels are also increased in conditions associated with hepatic regeneration, such as acute hepatitis. We conducted a longitudinal study of the alpha 1-6 fucosylation pattern of serum alpha-fetoprotein in ten patients with acute hepatitis and compared it to that of transferrin and alpha 1-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

alpha-Fetoprotein was hyperfucosylated and remained stable throughout the course of the disease. In contrast, serum transferrin and alpha 1-antitrypsin gradually became hyperfucosylated during the course of acute hepatitis. The transferrin and alpha 1-antitrypsin fucosylation indexes correlated with each other, but not with the alpha-fetoprotein fucosylation index. No correlation was found between alpha-fetoprotein, alpha 1-antitrypsin and transferrin fucosylation indexes and the corresponding glycoprotein serum levels.

CONCLUSIONS

Hyperfucosylation of alpha-fetoprotein is not specific to hepatocellular carcinoma. Increased alpha 1-6 fucosylation should not be considered solely as a tumour marker, but might also reflect cell proliferation. The study of alpha 1-6 hyperfucosylation 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.