Altered glycosylation and expression of plasma alpha-1-acid glycoprotein and haptoglobin in rheumatoid arthritis

Altered glycosylation patterns in plasma proteins are found to be associated with the pathogenesis of various malignancies and autoimmune disorders. Our previous studies demonstrated the occurrence of some differentially glycosylated plasma proteins in rheumatoid arthritis (RA) patients. The current study was conducted to evaluate the alterations in expression and glycosylation of major acute phase proteins from wheat germ agglutinin enriched RA patients’ plasma. Immunoblotting studies revealed a significant enhancement in the plasma levels of alpha-1 acid glycoprotein (AGP) and haptoglobin (Hp) in RA patients with respect to healthy controls. Monosaccharide analysis by high performance anion exchange-chromatography with pulse amperometric detection showed significant variations in the relative percentage of galactose, glucosamine and mannose in AGP and of mannose in Hp in RA patients. Altered patterns of mannosylation in AGP and Hp were also established by enzyme linked immunosorbent assay and Western blotting using Concanavalin-A lectin. These results could give information for understanding the disease pathogenesis and may provide an insight into the development and progression of the disease.