• I Pablos, S Eichhorn, Y Machado, P Briza, A Neunkirchner, B Jahn-Schmid, S Wildner, W T Soh, C Ebner, J-W Park, W F Pickl, N Arora, S Vieths, F Ferreira, and G Gadermaier.
• Division of Allergy and Immunology, Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
• Allergy. 2018 Feb 1; 73 (2): 431-441.

BackgroundArt v 1, Amb a 4, and Par h 1 are allergenic defensin-polyproline-linked proteins present in mugwort, ragweed, and feverfew pollen, respectively. We aimed to investigate the physicochemical and immunological features underlying the different allergenic capacities of those allergens.MethodsRecombinant defensin-polyproline-linked proteins were expressed in E. coli and physicochemically characterized in detail regarding identity, secondary structure, and aggregation status. Allergenic activity was assessed by mediator releases assay, serum IgE reactivity, and IgE inhibition ELISA using sera of patients from Austria, Canada, and Korea. Endolysosomal protein degradation and T-cell cross-reactivity were studied in vitro.ResultsDespite variations in the proline-rich region, similar secondary structure elements were observed in the defensin-like domains. Seventy-four percent and 52% of the Austrian and Canadian patients reacted to all three allergens, while Korean patients were almost exclusively sensitized to Art v 1. This was reflected by IgE inhibition assays demonstrating high cross-reactivity for Austrian, medium for Canadian, and low for Korean sera. In a subgroup of patients, IgE reactivity toward structurally altered Amb a 4 and Par h 1 was not changed suggesting involvement of linear epitopes. Immunologically relevant endolysosomal stability of the defensin-like domain was limited to Art v 1 and no T-cell cross-reactivity with Art v 125-36 was observed.ConclusionsDespite structural similarity, different IgE-binding profiles and proteolytic processing impacted the allergenic capacity of defensin-polyproline-linked molecules. Based on the fact that Amb a 4 demonstrated distinct IgE-binding epitopes, we suggest inclusion in molecule-based allergy diagnosis.© 2017 The Authors Allergy Published by John Wiley / Sons Ltd.

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