Medline ® Abstracts for References 31,32
of 'Clinical manifestations and diagnosis of oral allergy syndrome (pollen-food allergy syndrome)'
Cooking birch pollen-related food: divergent consequences for IgE- and T cell-mediated reactivity in vitro and in vivo.
Bohle B, Zwölfer B, Heratizadeh A, Jahn-Schmid B, Antonia YD, Alter M, Keller W, Zuidmeer L, van Ree R, Werfel T, Ebner C
J Allergy Clin Immunol. 2006;118(1):242.
BACKGROUND: The major birch pollen allergen Bet v 1 cross-reacts with homologous food allergens, resulting in IgE-mediated oral allergy syndromes (OASs). To avoid this food, allergy allergologists and guidebooks advise patients to consume birch pollen-related foods after heating.
OBJECTIVE: We sought to evaluate whether cooked Bet v 1-related food allergens induce IgE- and T cell-mediated reactions in vitro and in vivo.
METHODS: Recombinant Bet v 1, Mal d 1 (apple), Api g 1 (celery), and Dau c 1 (carrot) were incubated at increasing temperatures. Protein structures were determined by means of circular dichroism. Mediator release was tested in basophil activation assays. PBMCs and Bet v 1-specific T-cell lines with known epitope specificity were stimulated with native and cooked food allergens. Patients with birch pollen allergy who experienced OAS and the exacerbation of atopic dermatitis (AD) on ingestion of fresh apple, celery,or carrot were retested in double-blind, placebo-controlled food challenges with the respective foods in cooked form.
RESULTS: In vitro, cooked food allergens lost the capacity to bind IgE and to induce mediator release but had the same potency to activate Bet v 1-specific T cells as native proteins. In vivo, ingestion of cooked birch pollen-related foods did not induce OAS but caused atopic eczema to worsen.
CONCLUSION: T-cell cross-reactivity between Bet v 1 and related food allergens occurs independently of IgE cross-reactivity in vitro and in vivo. In patients with AD, the resulting immune reaction can even manifest as late eczematous skin reactions. Therefore the view that cooked pollen-related foods can be consumed without allergologic consequences should be reconsidered.
CLINICAL IMPLICATIONS: Symptom-free consumed pollen-related food allergens might cause T cell-mediated late-phase skin reactions in patients with pollen allergy and AD.
Department of Pathophysiology, Center for Physiology and Pathophysiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. firstname.lastname@example.org
Gastrointestinal digestion of Bet v 1-homologous food allergens destroys their mediator-releasing, but not T cell-activating, capacity.
Schimek EM, Zwölfer B, Briza P, Jahn-Schmid B, Vogel L, Vieths S, Ebner C, Bohle B
J Allergy Clin Immunol. 2005;116(6):1327.
BACKGROUND: Food allergy to apples, hazelnuts, and celery is frequent in individuals with birch pollen allergy because IgE antibodies specific for the major birch pollen allergen, Bet v 1, cross-react with structurally related allergens in these foods. In addition, T lymphocytes specific for Bet v 1 also cross-react with these dietary proteins.
OBJECTIVE: We sought to evaluate the effects of simulated gastrointestinal degradation of Bet v 1-related food allergens on their mediator-releasing and T cell-activating capacity.
METHODS: Recombinant Mal d 1, Cor a 1.04, and Api g 1 were incubated separately with pepsin and trypsin. Binding of IgE was tested in immunoblots. After successive incubation with both enzymes, allergens were tested in mast cell mediator release assays and used to stimulate PBMCs and Bet v 1-specific T-cell lines and clones. Proteolytic fragments of allergens were analyzed and sequenced by means of mass spectrometry.
RESULTS: Pepsin completely destroyed IgE binding of all allergens within 1 second, and trypsin completely destroyed IgE binding of all allergens within 15 minutes, except for the major hazelnut allergen, which remained intact for 2 hours of trypsinolysis. Allergens after gastrointestinal digestion did not induce basophil activation but induced proliferation in PBMCs from allergic and nonallergic individuals. Digested Mal d 1 and Cor a 1.04 still activated Bet v 1-specific T cells, whereas digested Api g 1 did not. Different proteolytic fragments of Mal d 1 and Cor a 1.04 matching relevant Bet v 1 T-cell epitopes were found.
CONCLUSION: Gastrointestinal degradation of Bet v 1-related food allergens destroys their histamine-releasing, but not T cell-activating, property. Our data emphasize that birch pollen-related foods are relevant activators of pollen-specific T cells.
Department of Pathophysiology, Center for Physiology and Pathophysiology, Medical University of Vienna, Austria.