Study of antibody repertoire to oligosaccharide fragments of polyglucosamines and galactosaminoglycans in sera from healthy human donors

Naturally circulating antibodies could dramatically change the activity of immunogens. In some cases, cross-interference between antibodies led to the loss of their opsonizing ability. Therefore, the study of antibody repertoire in blood sera of healthy donors is helpful for the development of vaccines and diagnostic kits. Levels of antibodies to fragments of biologically significant glucosamine and galactosamine polysaccharides and their N -acetylated derivatives were first studied in blood sera of 34 healthy donors using six biotinylated carbohydrate ligands. The highest titer of antibodies was found to poly-β-(1→6)- N -acetylglucosamine (PNAG), including its fully de- N -acetylated fragment. High antibody titers to the galactosaminoglycan (GG) fragments were also detected. For both PNAG and GG, the level of antibodies to N -acetylated ligands was higher than to the ligands with free amino groups. A correlation between the antibody titers for the respective N -acetylated and N -deacetylated forms was observed, which may suggest a cross interaction. No significant amounts of the antibodies to the chitooligosaccharides were detected. The results obtained will help to rationally plan further immunological studies aimed at the development of new vaccines and diagnostic kits.