engleski

Post B-cell sialylation in mice analyzed by xCGE- LIF

Immunoglobulin G (IgG) is one of key molecules in humoral immunity. Its effector functions are engaged through interactions with various Fcγ and other receptors and depend (among other things) on the type of the N-glycan structure attached to the Fc portion of the molecule. The presence of terminal sialic acids on this glycan is considered responsible for the anti- inflammatory properties of IgG. Recently it was proposed that IgG sialylation in mice can occur in the extracellular environment of the bloodstream, independent of the B-cell secretory pathway. Trying to verify and further investigate this finding, the aim of this study was to confirm the existence and examine the extent of the B-cell independent sialylation of IgG in mice. To this purpose, desialylated intravenous immunoglobulin (IVIg) preparation was administered intravenously to ST6Gal1-/- and µMT-/- mice (lacking endogenous IgG) on C57BL/6 background. Blood was collected before and 2, 4 and 6 days after IVIg administration, IgG isolated from the serum on a protein G monolithic plate, glycans released by protein N-glycosidase F, labeled with 8-aminopyrene- (1, 3, 6)-trisulfonic acid and analyzed by multiplexed capillary gel electrophoresis with laser-induced fluorescence detection (xCGE- LIF). Data analysis was performed by glyXtool software. We observed no change in the N-glycan profile of desialylated IVIg in the ST6Gal-/- mice. However, new glycan structures corresponding to mouse IgG sialylated N-glycans were observed in µMT-/- mice at low levels, indicating a presence of extrinsic sialylation in the mouse bloodstream.

capillary gel electrophoresis, IgG, sialylation

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