engleski

Fucosylation of IgG is increased in juvenile chronic arthritis

Oligosaccharide structures attached to IgG were suggested to have an important role in the development of juvenile chronic arthritis. We have measured levels of fucose moieties attached to IgG heavy chains in 34 juvenile chronic arthritis patients and 13 control individuals. IgG was purified from 0.7 ml of serum, separated by electrophoresis and transferred onto PVDF membrane. Fucose moieties attached to heavy chains were detected using biotin-labeled UEA I lectin followed by streptavidine-biotinylated alkaline phosphatase complex. We found that juvenile chronic arthritis patients have 2.4 times more fucose attached to IgG heavy chains than control individuals. This was highly surprising because several studies indicated that in healthy individuals over 80% of N-linked oligosaccharides on IgG are already fucosylated. The only plausible explanation for so extensive increase in fucosylation was that it originated from the increase in O-linked fucose moieties. Indeed, after removing N-linked oligosaccharides using peptide-N-glycosidase F, we have found that even in healthy individuals approximately 50% of fucose moieties on IgG heavy chains are linked through an O-glycosidic bond. In juvenile chronic arthritis up to 80% of fucose moieties were found to be O-linked. Juvenile chronic arthritis patients had averagely 3,3 times more O-linked fucoses than control individuals, confirming that increase in the overall fucosylation levels mostly derives from O-linked carbohydrates. These results suggest that more attention should be focused on O-linked oligosaccharides on IgG in the future because they appear to be reliable and rapid tool to diagnose juvenile chronic arthritis.

juvenile chronic arthritis; IgG; fucose; O-linked oligosaccharides; lectins

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