To look for oligosaccharide structural variants of IgG that may be unique to specific rheumatic diseases.
Using normal-phase high-performance liquid chromatography technology, a comparison was made of the oligosaccharide pools released from serum IgG from patients with systemic lupus erythematosus (SLE) (n = 10), ankylosing spondylitis (AS) (n = 10), primary Sjögren's syndrome (n = 6), juvenile chronic arthritis (JCA) (n = 13), psoriatic arthritis (n = 9), rheumatoid arthritis (RA) (n = 5), and healthy control individuals (n = 19).
The oligosaccharide pools were resolved into 13 peaks and the relative proportions of the peaks in each disease group was significantly different from that in healthy controls (P < 0.0001-0.05). A characteristic serum IgG oligosaccharide profile, or sugar print, for each of the rheumatic diseases was found. The sugar prints exhibited a range of glycosylation patterns whereby all RA (P < 0.0001) and JCA (P < 0.006) patients had predominantly agalactosyl structures, while SLE (P < 0.03-0.0001) and AS (P < 0.025-0.0001) patients had predominantly digalactosyl structures.
The data suggest that each disease is associated with a specific mechanism that gives rise to alterations in the normal glycosylation pattern of IgG. Sugar printing of IgG is therefore a potential means for the differentiation of rheumatic diseases and may provide insight into disease pathogenesis.