Structural analysis of N-glycans from allergenic grass, ragweed and tree pollens: core alpha1,3-linked fucose and xylose present in all pollens examined.

The N-glycans from soluble extracts of ten pollens were examined. The pyridylaminated oligosaccharides derived from these sources were subject to gel filtration and reverse-phase HPLC, in conjunction with exoglycosidase digests, and in some cases matrix-assisted laser desorption-ionisation mass spectrometry. In comparison to known structures, it was possible to determine the major structures of the N-glycans derived from Kentucky blue grass (Poa pratensis), rye (Secale cerale), ryegrass (Lolium perenne), short ragweed (Ambrosia elatior), giant ragweed (Ambrosia trifida), birch (Betula alba), hornbeam (Carpinus betulus), horse chestnut (Aesculus hippocastanum), olive (Olea europaea) and snake-skin pine (Pinus leucodermis) pollen extracts. For grass pollens the major glycans detected were identical in properties to: [structure in text] Grass pollens also contained some minor structures with one or two non-reducing terminal N-acetylglucosamine residues. In the ragweed pollens, the major structures carried core alpha1,3-linked fucose with or without the presence of xylose. In tree pollen extracts, the major structures were either xylosylated, with or without fucose and terminal N-acetylglucosamine residues, with also significant amounts of oligomannose structures. These results are compatible with the hypothesis that the carbohydrate structures are another potential source of immunological cross-reaction between different plant allergens.