Core alpha1,3-fucose is a key part of the epitope recognized by antibodies reacting against plant N-linked oligosaccharides and is present in a wide variety of plant extracts

Carbohydrates have been suggested to account for some IgE cross- reactionsbetween various plant, insect, and mollusk extracts, while some IgGantibodies have been successfully raised against plant glycoproteins. A ratmonoclonal antibody raised against elderberry abscission tissue (YZ1/2.23)and rabbit polyclonal antiserum against horseradish peroxidase werescreened for reactivity in enzyme-linked immunosorbent assay against arange of plant glycoproteins and extracts as well as neoglycoproteins, beevenom phospholipase, and several animal glycoproteins. Of theoligosaccharides tested, Man3XylFucGlcNAc2(MMXF3) derived from horseradishperoxidase was the most potent inhibitor of the reactivity of both YZ1/2.23and anti- horseradish peroxidase to native horseradish peroxidaseglycoprotein. The reactivity of YZ1/2. 23 and anti-horseradish peroxidaseagainst Sophora japonica lectin was most inhibited by a neoglycoconjugateof bromelain glycopeptide cross-linked to bovine serum albumin, while thedefucosylated form of this conjugate was inactive as an inhibitor. A widerange of plant extracts was found to react against YZ1/2.23 andanti-horseradish peroxidase, with particularly high reactivities recordedfor grass pollen and nut extracts. All these reactivities were inhibitablewith the bromelain glycopeptide/bovine serum albumin conjugate. Bee venomphospholipase and whole bee venom reacted weakly with YZ1/2.23 but morestrongly with anti-horseradish peroxidase in a manner inhibitable with thebromelain glycopeptide/bovine serum albumin conjugate, while hemocyaninfrom Helix pomatia reacted poorly with YZ1/2.23 but did react withanti-horseradish peroxidase. It is concluded that the alpha1, 3-fucoseresidue linked to the chitobiose core of plant glycoproteins is the mostimportant residue in the epitope recognized by the two antibodies studied,but that the polyclonal anti-horseradish peroxidase antiserum also containsantibody populations that recognize the xylose linked to the core mannoseof many plant and gastropod N-linked oligosaccharides.