IgA glycosylation abnormalities in the serum of patients with primary Sjögren's syndrome.

Since there is no information regarding the glycosylation status of immunoglobulin A (IgA) in patients with primary Sjögren's syndrome (pSS), the sialic acid and galactose contents of IgA1 and IgA2 were evaluated in 17 pSS patients and in 14 normal controls (NC), using new enzyme-linked immunosorbent assays. The proportion of sialylated IgA1 and IgA2 was augmented (p < 0.001 and < 0.05, compared with NC), whereas that of galactosylated IgA1 and IgA2 was reduced (p < 0.01 and < 0.02, respectively). The level of SA IgA1 correlated the amount of IgA-containing immune complexes (p < 0.01), serum IgA (p < 0.01) and IgA-rheumatoid factor (p < 0.01). This demonstrates a number of IgA abnormalities in pSS patients. There were no correlations between SA and Gal, however, nor could any difference be ascribed to extraglandular manifestations.