During the last decades the glycans of the most abundant immunoglobulin (Ig), IgG, got a lot of attention, since the biological activity of human IgG is directly influenced by its glycosylation status. The Fc N-glycosylation can modulate its function in an inflammatory or anti-inflammatory mode of action. The posttranslational addition or removal of distinct sugar residues may lead to an increased or decreased effect on cell-dependent cytotoxicity, or an antibody-dependent cellular phagocytosis to name a few. For example, sialylated IgGs are less inflammatory than asialylated IgGs. Interestingly, the glycosylation seems to change during aging and different diseases. Furthermore, inflammatory glycan patterns on IgGs are reduced during pregnancy, but are increased in individuals with autoimmune diseases or chronic infections as well as a tumor relapse in comparison to healthy individuals.
We want to investigate the glycosylation status and its biological impact in cattle and other farm animals. These studies should expand the knowledge of the importance of glycosylation of antibodies in livestock animals to improve their animal welfare. To achieve this, we purify IgGs from biological samples like milk in addition to blood and released enzymatically the N-glycans. After fluorescence labelling glycans were separated via hydrophilic interaction chromatography (HILIC) and subsequently analyzed by ESI-MS. In addition, the sialic acids were separately analyzed by reverse phase HPLC. The first results indicate that bovine IgGs are sialylated with higher amounts of N-glycolylneuraminic acid (Neu5Gc) compared to N-acetylneuraminic acid (Neu5Ac). In contrast, swine IgGs are less sialylated and contain only minor amounts of Neu5Gc. Thus, a species specific sialylation of IgGs takes place.