Schimek Eva Maria, Zwölfer Bettina, Briza Peter, Jahn-Schmid Beatrice, Vogel Lothar, Vieths Stefan, Ebner Christof, Bohle Barbara
Department of Pathophysiology, Center for Physiology and Pathophysiology, Medical University of Vienna, Austria.
J Allergy Clin Immunol. 2005 Dec;116(6):1327-33. doi: 10.1016/j.jaci.2005.09.007. Epub 2005 Nov 2.
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.
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.
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.
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.
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.
对桦树花粉过敏的个体中，对苹果、榛子和芹菜的食物过敏很常见，因为针对主要桦树花粉过敏原Bet v 1的IgE抗体与这些食物中结构相关的过敏原发生交叉反应。此外，针对Bet v 1的T淋巴细胞也与这些膳食蛋白发生交叉反应。
我们试图评估模拟胃肠道降解Bet v 1相关食物过敏原对其介质释放和T细胞激活能力的影响。
将重组Mal d 1、Cor a 1.04和Api g 1分别与胃蛋白酶和胰蛋白酶孵育。在免疫印迹中检测IgE的结合。在与两种酶连续孵育后，在肥大细胞介质释放试验中检测过敏原，并用于刺激外周血单核细胞（PBMC）以及Bet v 1特异性T细胞系和克隆。通过质谱分析过敏原的蛋白水解片段并进行测序。
胃蛋白酶在1秒内完全破坏了所有过敏原的IgE结合，胰蛋白酶在15分钟内完全破坏了所有过敏原的IgE结合，但主要榛子过敏原在胰蛋白酶消化2小时内保持完整。胃肠道消化后的过敏原未诱导嗜碱性粒细胞活化，但诱导了过敏和非过敏个体的PBMC增殖。消化后的Mal d 1和Cor a 1.04仍能激活Bet v 1特异性T细胞，而消化后的Api g 1则不能。发现了与相关Bet v 1 T细胞表位匹配的Mal d 1和Cor a 1.04的不同蛋白水解片段。
Bet v 1相关食物过敏原的胃肠道降解破坏了它们释放组胺的特性，但未破坏T细胞激活特性。我们的数据强调，桦树花粉相关食物是花粉特异性T细胞的相关激活剂。
