Structural changes of immunoglobulin G oligosaccharides with age in healthy human serum

Abstract

Age-related changes of IgG N-linked oligosaccharides isolated from normal human serum are reported for 403 individuals (male 227 and female 176), varying in age from 0 to 85 years. The IgG N-linked oligosaccharides were released from the protein by digestion with a glycoamidase and reductively aminated with the fluorescent reagent, 2-aminopyridine. The mixture of pyridylaminated oligosaccharides was separated at high resolution by HPLC using a reverse-phase column. From the results of neutral oligosaccharide analysis, agalactosyl glycoform and bisecting GlcNAc-containing glycoform were shown to increase with increasing age. Spearman's correlation coefficients were 0.503 and 0.473, respectively. Thus, in healthy people, an increase of both types of glycoforms correlates weakly with age. In addition, differences were demonstrated between male and female groups in their twenties. The quantity of agalactosyl glycoform was found to be lower in females than in males. No significant differences, however, were observed in the quantity of bisecting GlcNAc-containing glycoforms between males and females. Abbreviations: Gal, D-galactose: GlcNAc, N-acetyl-D-glucosamine; Man, D-mannose; Fc, C-terminal half of the heavy chain dimers of IgG; HPLC, high-performance liquid chromatography; IgG, immunoglobulin G; ODS, octadecylsilyl; PA, pyridylamino