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Vienna, Austria

Hochwallner H.,Medical University of Vienna | Schulmeister U.,Medical University of Vienna | Swoboda I.,Christian Doppler Laboratory | Focke-Tejkl M.,Christian Doppler Laboratory | And 17 more authors.
Journal of Allergy and Clinical Immunology | Year: 2010

Background: α-Lactalbumin (α-La) is a major cow's milk (CM) allergen responsible for allergic reactions in infants. Objective: We performed molecular, structural, and immunologic characterization of α-La. Methods: Recombinant α-lactalbumin (rα-La) was expressed in Escherichia coli, purified to homogeneity, and characterized by means of mass spectrometry and circular dichroism, and its allergenic activity was studied by using microarray technology, as well as in a basophil histamine release assay. IgE epitope mapping was performed with synthetic peptides. Results: According to circular dichroism analysis, rα-La represented a folded protein with a high thermal stability and refolding capacity. rα-La reacted with IgE antibodies from 57.6% of patients with CM allergy (n = 66) and induced the strongest basophil degranulation with sera from patients with CM allergy who had exhibited gastrointestinal symptoms or severe systemic reactions on CM exposure. rα-La contained sequential and conformational IgE epitopes. Superposition of IgE-reactive peptides onto the 3-dimensional structure of α-La revealed a close vicinity of the N- and C-terminal peptides within a surface-exposed patch. Conclusions: rα-La can be used for the diagnosis of patients with severe allergic reactions to CM and serves as a paradigmatic tool for the development of therapeutic strategies for CM allergy. © 2010 American Academy of Allergy, Asthma & Immunology.

Geroldinger-Simic M.,Medical University of Vienna | Kinaciyan T.,Medical University of Vienna | Nagl B.,Medical University of Vienna | Baumgartner-Durchschlag U.,Biomay AG | And 8 more authors.
Journal of Allergy and Clinical Immunology | Year: 2013

Background: Antibodies and T cells specific for the major birch pollen allergen Bet v 1 cross-react with structurally related food allergens, such as Mal d 1 in apple. Objective: We sought to evaluate the effects of oral uptake of Mal d 1 on the allergen-specific immune response in patients with birch pollen allergy. Methods: Patients received 50 μg of rBet v 1 sublingually on 2 consecutive days outside of the birch pollen season. One year later, equal amounts of rMal d 1 were administered. Blood samples were collected before and after oral exposure, as well as before and after the intermediate birch pollen season. Allergen-specific IgE levels were determined by using ImmunoCAP. Proliferation of allergen-stimulated PBMCs was assessed, as well as the expression of IL-5, IL-13, IL-10, IFN-γ, and forkhead box protein 3 (Foxp3) in isolated T cells (real-time PCR). Allergen-specific T-cell lines were analyzed for epitope recognition. Results: Orally administered Bet v 1 transiently reduced Bet v 1-specific serum IgE levels, as well as Bet v 1- and Mal d 1-induced T-cell proliferation, and enhanced the expression of IL-5, IL-10, and Foxp3. Orally applied Mal d 1 significantly decreased Bet v 1- and Mal d 1-specific IgE levels and induced IL-5 and IL-10 but no Foxp3 expression. In contrast to Bet v 1, Mal d 1 triggered IFN-γ production and T cells with a different epitope repertoire. Inhalation of birch pollen significantly enhanced allergen-specific IgE levels, T-cell proliferation, and IL-5, IL-10, IL-13, and Foxp3 expression. Conclusion: Two sublingual administrations of 50 μg of Mal d 1 were well tolerated and induced transient immune responses seen during peripheral tolerance development. Thus recombinant Mal d 1 might be suitable and relevant for sublingual treatment of birch pollen-related apple allergy. © 2012 American Academy of Allergy, Asthma & Immunology.

Geroldinger-Simic M.,Medical University of Vienna | Zelniker T.,Medical University of Vienna | Aberer W.,Medical University of Graz | Ebner C.,Allergy Clinic Reumannplatz | And 8 more authors.
Journal of Allergy and Clinical Immunology | Year: 2011

Background: Patients with birch pollen allergy often develop allergic reactions to plant foods. Objective: To evaluate the prevalence, main symptoms, and triggers of birch pollen-related food allergy and the role of food-specific IgG4 antibodies in food tolerance. Methods: Food-induced symptoms were evaluated in 225 individuals with birch pollen allergy by using a standardized questionnaire. IgE and IgG4 levels specific for the major birch pollen allergen Bet v 1 and birch profilin Bet v 2 and the Bet v 1 homologs in apple (Mal d 1) and hazelnut (Cor a 1) were quantified by ImmunoCAP. Mock-treated and IgG-depleted sera from patients tolerating hazelnuts in food challenges were compared for their inhibitory activity for binding of Cor a 1-IgE complexes to B cells. Results: In total, 73% of the study population experienced food allergy, which was perennial in 86% of the affected individuals. The oral allergy syndrome was the main clinical manifestation. However, more than 58% of the patients also experienced food-induced rhinoconjunctivitis. Apples and hazelnuts were identified as the most frequent triggers. Food allergy correlated with IgE reactivity to Bet v 1 but not to Bet v 2. Mal d 1-specific and Cor a 1-specific IgG4/IgE ratios were significantly higher in food-tolerant individuals than individuals with food allergy. Sera from IgG4-positive food-tolerant patients possessed IgG-dependent IgE-inhibitory activity. Conclusion: Birch pollen-related food allergy is highly prevalent and often perennial. High food allergen-specific IgG4/IgE ratios seem associated with food tolerance, potentially because specific IgG4 blocks IgE binding to food allergens. Thus, the presence of food allergen-specific IgG4 antibodies is no diagnostic marker for birch pollen-related food allergy. © 2010 American Academy of Allergy, Asthma and Immunology.

Vejvar E.,Christian Doppler Laboratory | Himly M.,Christian Doppler Laboratory | Briza P.,Christian Doppler Laboratory | Eichhorn S.,Christian Doppler Laboratory | And 4 more authors.
Molecular Nutrition and Food Research | Year: 2013

Scope: Apium graveolens represents a relevant food allergen source linked with severe systemic reactions. We sought to identify an IgE-binding nonspecific lipid transfer protein (nsLTP) in celery tuber. Methods and results: A low molecular weight protein exclusively present in celery tuber was purified and designated Api g 6. The entire protein sequence was obtained by MS and classified as member of the nsLTP2 family. Api g 6 is monomeric in solution with a molecular mass of 6936 Da. The alpha-helical disulfide bond-stabilized structure confers tremendous thermal stability (Tm > 90°C) and high resistance to gastrointestinal digestion. Endolysosomal degradation demonstrated low susceptibility and the presence of a dominant peptide cluster at the C-terminus. Thirty-eight percent of A. graveolens allergic patients demonstrated IgE reactivity to purified natural Api g 6 in ELISA and heat treatment did only partially reduce its allergenic activity. No correlation in IgE binding and limited cross-reactivity was observed with Api g 2 and Art v 3, nsLTP1 from celery stalks and mugwort pollen. Conclusion: Api g 6, a novel nsLTP2 from celery tuber represents the first well-characterized allergen in this protein family. Despite similar structural and physicochemical features as nsLTP1, immunological properties of Api g 6 are distinct which warrants its inclusion in molecule-based diagnosis of A. graveolens allergy. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ackerbauer D.,Medical University of Vienna | Bublin M.,Medical University of Vienna | Radauer C.,Medical University of Vienna | Varga E.-M.,Medical University of Graz | And 7 more authors.
International Archives of Allergy and Immunology | Year: 2015

Background: Peanut allergy develops after primary sensitization to peanut allergens and/or IgE cross-sensitization with homologous allergens from various plants. Therefore, heterogeneous patterns of sensitization to individual peanut allergens are observed in different countries. The aim of this study was to examine the IgE sensitization patterns of Austrian peanut-allergic patients. Methods: Sera from 65 peanut-allergic patients and 20 peanut-tolerant atopics were obtained in four Austrian allergy clinics. Sensitization patterns against peanut allergens Ara h 1-3, 6, 8 and 9 were identified by ImmunoCAP and ImmunoCAP ISAC. Results: Austrian peanut-allergic patients were sensitized to Ara h 2 and 6 (71%), followed by Ara h 1 (62%), Ara h 8 (45%), Ara h 3 (35%) and Ara h 9 (11%). All sera containing Ara h 2-specific IgE were also positive for Ara h 6, with Ara h 6-specific IgE levels significantly (p < 0.05) higher compared with Ara h 2. Twelve percent displayed IgE reactivity exclusively to Ara h 8. Peanut extract and Ara h 8 showed low diagnostic specificities of 25 and 10%, respectively. The other peanut allergens showed 100% specificity. Diagnostic sensitivities determined by ImmunoCAP ISAC and ImmunoCAP were highly similar for Ara h 2, 3 and 8. Conclusions: The majority of symptomatic peanut-allergic patients are sensitized to Ara h 2 and Ara h 6. In peanut-symptomatic patients with additional birch pollen allergy, other peanut allergens, especially Ara h 8, should be tested when IgE reactivity to Ara h 2 is absent. © 2015 S. Karger AG, Basel.

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