Lehrer S B, Horner W E, Reese G
Clinical Immunology and Allergy Section, Tulane University Medical Center, Orleans, LA 70112, USA.
Crit Rev Food Sci Nutr. 1996 Jul;36(6):553-64. doi: 10.1080/10408399609527739.
In recent years, a number of agricultural crops have been developed with recombinant DNA technology. Because the transferred genes code for proteins that are ordinarily not present in these particular foods, there is concern about the potential allergenicity of these new crop varieties. Foods contain many proteins; however, only a small fraction are allergens. Although the structural properties of proteins that cause allergic reactions have not been characterized completely, known food allergens in general have molecular weights between 10 and 70 kDa, stimulate the immune response (induce the production of allergen-specific IgE), and are stable molecules that are resistant to processing, cooking, and digestion. Although any type of food is potentially allergenic, the majority of food allergies are caused by a small group of foods (cows' milk, nuts, legumes, eggs, seafood). Cross-reactivities occur within a given food group and between foods and seemingly unrelated proteins. Even though most transgenic foods are considered safe, biotechnological manipulation can affect crop allergenicity. The safety evaluation of transgenic foods is relatively easy when the allergenicity of the gene sources are known. The recombinant food can be assayed using traditional in vitro inhibition assays. Recently, reduced allergen content of biotechnologically altered rice was shown. In contrast, increased allergenicity was demonstrated in transgenic soybeans after a methionine- and cystine-rich protein from Brazil nuts, identified as a major Brazil nut allergen, was expressed in soybean to increase its content of sulfur-rich amino acids. The most difficult issue regarding transgenic food allergenicity is the effect of transfer of proteins of unknown allergenicity. The challenge is to determine whether these proteins are allergenic as there is no generally accepted, established, definitive procedure to define or predict a protein's allergenicity. Comparing the structures of the transferred protein with known allergens and allergen epitopes could be one approach. Additionally, Th-2 cell stimulation, the production of IL-4, and IgE antibody induction in animal models may help to evaluate the potential allergenicity of a protein. In conclusion, there is no evidence that recombinant proteins in newly developed foods are more allergenic than traditional proteins. The evidence suggests that the vast majority of these proteins will be completely safe for the consumer. The concern is that if a few transgenic foods cause serious allergic reactions, this could undermine the public's confidence in such products. It is essential that proper guidelines are established and tests are developed to assure that this will not occur.
近年来，利用重组DNA技术培育出了许多农作物品种。由于转入的基因编码的蛋白质通常不存在于这些特定的食物中，人们对这些新作物品种的潜在致敏性表示担忧。食物含有许多蛋白质；然而，只有一小部分是过敏原。虽然引起过敏反应的蛋白质的结构特性尚未完全明确，但已知的食物过敏原一般分子量在10至70 kDa之间，能刺激免疫反应（诱导产生过敏原特异性IgE），并且是对加工、烹饪和消化具有抗性的稳定分子。虽然任何类型的食物都有潜在的致敏性，但大多数食物过敏是由一小类食物（牛奶、坚果、豆类、鸡蛋、海鲜）引起的。在特定食物组内以及食物与看似不相关的蛋白质之间会发生交叉反应。尽管大多数转基因食品被认为是安全的，但生物技术操作可能会影响作物的致敏性。当基因来源的致敏性已知时，转基因食品的安全性评估相对容易。重组食品可以使用传统的体外抑制试验进行检测。最近，有研究表明生物技术改造的大米中过敏原含量降低。相反，将巴西坚果中一种富含蛋氨酸和胱氨酸的蛋白质（被确定为巴西坚果的主要过敏原）在大豆中表达以增加其富含硫氨基酸的含量后，转基因大豆的致敏性增加。关于转基因食品致敏性最棘手的问题是未知致敏性蛋白质的转移效应。面临的挑战是确定这些蛋白质是否具有致敏性，因为目前尚无普遍接受、既定的明确程序来定义或预测蛋白质的致敏性。将转入蛋白质的结构与已知过敏原和过敏原表位进行比较可能是一种方法。此外，在动物模型中进行Th - 2细胞刺激、IL - 4的产生以及IgE抗体诱导可能有助于评估蛋白质的潜在致敏性。总之，没有证据表明新开发食品中的重组蛋白质比传统蛋白质更具致敏性。证据表明，这些蛋白质中的绝大多数对消费者来说将是完全安全的。令人担忧的是，如果少数转基因食品引发严重的过敏反应，这可能会削弱公众对这类产品的信心。必须制定适当的指导方针并开发相关测试，以确保不会出现这种情况。
