The Repertoire of Human Antiglycan Antibodies and Its Dynamics in the First Year of Life.

The repertoire of antiglycan antibodies of peripheral blood was studied using a microarray containing 487 glycan antigens: fragments of mammalian glycans (N- and O-chains of glycoproteins, as well as glycolipids) and also bacterial polysaccharides. The sera samples correspond to the third, sixth, and twelfth months of life. The infants were divided into four groups according to their nutrition type: breast milk, standard formula, and partially or extensively hydrolyzed formula. During the first year of life, the total amount of IgG decreased; presumably, the lifetime of maternal IgG in the newborns' bloodstream is much greater than is generally assumed. At the same time, the IgM content was low during the first six months and increased significantly by the twelfth month. The antiglycan IgM repertoire of one-year-old infants was still different from that of their mothers, as well as from the repertoire of unrelated donors, in particular, by the absence of antibodies against the Galß1-3GlcNAc (LeC) disaccharide, which is found in almost all healthy humans. It is noteworthy that the level of IgM of breast-fed infants was significantly lower than that of formula-fed by the twelfth month.

Changes in the repertoire of natural antibodies caused by immunization with bacterial antigens.

The repertoire of natural anti-glycan antibodies in naïve chickens and in chickens immunized with bacteria Burkholderia mallei, Burkholderia pseudomallei, and Francisella tularensis as well as with peptides from an outer membrane protein of B. pseudomallei was studied. A relatively restricted pattern of natural antibodies (first of all IgY against bacterial cell wall peptidoglycan fragments, L-Rha, and core N-acetyllactosamine) shrank and, moreover, the level of detectable antibodies decreased as a result of immunization.