SENSITIZATION MECHANISM OF FOOD ALLERGY BY PATHOGENESIS-RELATED PROTEINS DERIVED FROM PLANT FOODSTUFFS

近年来研究发现，病程相关蛋白（PR-P或防御蛋白，DF）在食物过敏中起重要作用。这些蛋白质中存在的结构相似性必须负责交叉反应的可能性。探讨PR-P或DF诱发IgE抗体和诱发过敏反应的原因是非常有趣的。本研究旨在探讨致敏后诱导IgE产生能力与其结构和/或功能的关系，并筛选植物性食物过敏患者血清中IgE抗体所识别的植物性食物提取物中的蛋白质。在植物性食物中发现了几种特异性的IgE结合变应原蛋白，这些蛋白被鉴定为致病相关蛋白。如马铃薯Betv 1（桦树花粉变应原）同源18 kDa变应原蛋白，胡萝卜亲环素20 kDa变应原蛋白，番茄木栓化相关过氧化物酶45 kDa变应原蛋白，谷胱甘肽S-转移酶37 kDa变应原蛋白，芜菁25 kDa铁氧还蛋白/NADH氧化还原酶。最后两个变应原蛋白质被证明增加在萝卜植物生长在温和的化学胁迫（水杨酸处理），表明这些蛋白质的致病蛋白和变应原性将增加压力负荷。此外，具有杀虫活性的重组致病蛋白PR-5d，计划转入马铃薯中，没有显示出与患者IgE抗体的结合能力。现在我们已经建立了一个过敏原数据库，供过敏原调查人员使用。

Recently, the pathogenesis-related proteins (PR-P or known as defense proteins, DF) were shown to play an important role in food allergy. Structural similarity present in these proteins must be responsible for the potential of cross reactivity. It is of very interesting to investigate why the PR-P or DF induces IgE antibodies and elicits allergic manifestation. This study aimed to investigate the relationship between the structure or/and function and the ability to induce IgE production after sensitization.We tried to screen the proteins in the extract of various plant foodstuffs which was recognized by IgE antibodies in sera of the patients allergic to plant food stuffs. Several unique proteins were found in plant foods as IgE binding allergenic proteins, which were identified to be pathogenesis-related proteins,. such as 18kDa allergenic protein homologous to Bet v1 (Birch pollen allergen) from potato, 20kDa allergenic protein of cyclophilin from carrot, 45kDa allergenic protein as suberization-associated peroxidase from tomato, 37kDa allergenic protein as glutathione S-transferase, and 25kDa feredoxine/NADH oxidoreductase fro turnip, respectively. Last two allergenic proteins were shown to increase in turnip plants grown under a mild chemical stress (salicylic acid treatment), indicating that these proteins were the pathogenesis proteins and the allergenicity would be increase by a stress loading. In addition, the recombinant pathogenesis protein, PR-5d which has an insecticide activity and will be planed to transfer into potato, did not show the binding ability to patients IgE antibodies. Now we have constructing a allergen database to be used for allergen investigators.