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

近年来，发病相关蛋白（PR-P或称为防御蛋白，DF）被证明在食物过敏中起重要作用。存在于这些蛋白质中的结构相似性一定是交叉反应的潜在原因。研究为什么PR-P或DF诱导IgE抗体并引起过敏表现是非常有趣的。本研究旨在探讨其结构或功能与致敏后诱导IgE产生能力之间的关系。我们试图在植物性食物过敏患者血清中筛选各种植物性食物提取物中能被IgE抗体识别的蛋白质。在植物性食物中发现了几种独特的蛋白作为IgE结合的致敏蛋白，这些蛋白被鉴定为致病相关蛋白。如马铃薯中同源于桦树花粉变应原的18kDa变应原蛋白、胡萝卜中同源于亲环蛋白的20kDa变应原蛋白、番茄中同源于亚化相关过氧化物酶的45kDa变应原蛋白、谷胱甘肽s转移酶的37kDa变应原蛋白、萝卜中同源于铁多醇/NADH氧化还原酶的25kDa变应原蛋白。最后两种致敏蛋白在轻度化学胁迫（水杨酸处理）下均呈增加趋势，说明这两种蛋白是致病蛋白，胁迫会增加致敏性。此外，重组发病蛋白PR-5d没有显示出与患者IgE抗体的结合能力，该蛋白具有杀虫活性，将计划转移到马铃薯中。现在我们正在构建过敏原数据库，供过敏原研究人员使用。

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.