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Abstract

In order to elucidate the relationship between glycosylation of IgG and aging, oligosaccharide structures of human IgG purified from sera of men and women aged 18 to 73 years were investigated. Oligosaccharides were liberated quantitatively from IgG by hydrazinolysis followed by N-acetylation and were tagged with p-aminobenzoic acid ethyl ester. The oligosaccharide structures were then analyzed by HPLC in conjunction with sequential exoglycosidase digestion. All IgG samples were shown to contain a series of biantennary complex type oligosaccharides which consisted of +/-Galbeta1-4GlcNAcbeta1-2Manalpha1-6(+/-GlcNAcbeta 1-4)(+/-Galbeta1-4GlcNAcbeta1-2Man(alpha)1-3)Man(beta)1-+ ++4GlcNAcbeta1-4(+/- Fucalpha1-6)GlcNAc and their mono- and disialo glycoforms in different ratios. In female IgG samples only, the incidence of non-galactosylated oligosaccharides with non-reducing terminal GlcNAc residues increased with aging (r>0.8), whereas that of digalactosylated oligosaccharides decreased (r<-0.8). A weaker correlation was observed between aging and the incidence of neutral and monosialo oligosaccharides in female IgG (r=0.461 and r= -0.538, respectively) and between aging and the incidence of oligosaccharides with a bisecting GlcNAc in both male and female IgG samples (r=0.566 and r=0.440, respectively). In addition, a significant change with aging in the galactosylation of IgG oligosaccharides was observed in females in their thirties, fifties, and sixties (p<0.02, p<0.01, and p<0.04, respectively). These findings may contribute to our understanding of autoimmune diseases such as rheumatoid arthritis in which glycosylation is involved.

Aberrant IgG galactosylation precedes disease onset, correlates with disease activity, and is prevalent in autoantibodies in rheumatoid arthritis

“…Indeed, previous studies have shown an age-dependent increase in sG0/G1 (55–57). Here, in addition to age, we used a series of multivariate analyses to assess the impact of CCP, disease duration and gender on the sG0/G1:DAS correlation.…”

Changes in Antigen-specific IgG1 Fc N-glycosylation Upon Influenza and Tetanus Vaccination

“…An optimized tryptic cleavage procedure was applied (23), and no tryptic missed cleavages were observed. On the basis of literature knowledge of IgG N -glycosylation (27–31) the nanoliquid chromatography-electrospray ionization (LC-ESI-MS) method allowed unambiguous assignment of 46 IgG glycopeptides species (18 glycoforms of IgG1, 10 of IgG4, and 18 of IgG2; Table II). Glycoforms having 5 N -acetylhexosamine residues were interpreted as bisected species (27–31).…”

Comparative Performance of Four Methods for High-throughput Glycosylation Analysis of Immunoglobulin G in Genetic and Epidemiological Research

“…Data processing and evaluation were performed with FlexAnalysis Software (Bruker Daltonics) and Microsoft Excel, respectively. Structural assignment of the detected glycoforms was performed on the basis of literature knowledge of IgG N -glycosylation (27–32). The data were baseline subtracted and the intensities (peak heights) of a defined set of 27 glycopeptides (16 glycoforms for IgG1 and 11 for IgG2&3) were automatically defined for each spectrum as described before (33).…”

“…Structural assignment of the detected glycoforms was performed on the basis of literature knowledge of IgG N -glycosylation (27–32). Relative intensities of 20 IgG1, 20 IgG2/3, and 10 IgG4 glycopeptide species were obtained by integrating and summing the first three isotopic peaks of both doubly and triply charged glycopeptides species followed by background correction and normalization to the total IgG subclass specific glycopeptide intensities.…”