食物过敏的定义、流行性、诊断及治疗

Food allergy： definitions, prevalence, diagnosis and therapy

食物过敏是异质性群体相关疾病，会通过一种或多种方式对多个器官造成影响。其反应的严重程度可从轻度的局部反应到全身性的过敏反应。从机制上来看，食物过敏是Th2细胞驱动的免疫紊乱疾病，食物特异性IgE是这种速发型不良反应的基础。过敏的部位和症状并不一定相同。食物过敏常会与自身免疫性（如乳糜泻）和非免疫性（如乳糖不耐受）的其他食物不良反应相混淆。为了正确诊断食物过敏，需要详细了解患者病史，检测特异性IgE，并进行经口激发试验来确诊。一些辅助因素（如运动、药物和酒精）有助于诱发食物过敏，会进一步增加诊断的复杂性。以食物提取物为基础的诊断试验并不能反映症状的严重程度，而检测单个食物致敏原IgE的新一代分子诊断技术，则能够为临床医生和患者提供可靠的症状严重程度依据。分子诊断还有助于确定食物过敏是直接源于对食物的暴露还是间接源于花粉过敏（交叉反应）。流行病学调查表明，桃过敏在欧洲主要是源于对桃的食用，而在中国则是源于对艾蒿花粉的初级致敏。但这两种情况都是由来自同一家族的致敏原分子介导的。流行病学调查深入揭示了食物过敏的病因、流行性及其所包含的风险因素，为预防食物过敏提供了循证策略。过去的十年中，食物过敏在发达国家盛行。经济发展和城市化进程都被认为会导致食物过敏流行性的增加，而且饮食习惯不同，过敏的食物也不同。目前，分子变态反应学和生物技术正在开发安全的免疫治疗方法，有望能够减轻日益加重的食物过敏负担。一种使用低致敏性突变重组分子的免疫疗法已经开始进行第一阶段临床试验的评估。食物致敏原名单的不断完善为转基因食品致敏性的评估提供了坚实基础。

Food allergy is phenotypically an extremely heterogeneous group of diseases affecting multiple organs, sometimes in an isolated way, sometimes simultaneously, with the severity of reactions ranging from mild and local to full-blown anaphylaxis. Mechanistically, it is defined as a Th2-driven immune disorder in which food-specific IgE antibodies are at the basis of immediate-type adverse reactions. The sites of sensitization and symptoms do not necessarily overlap. Food allergy, which is the theme of this paper, is often confused with other adverse reactions to food of both animmune （ e. g. , celiac disease ） and non- immune （e. g. , lactose intolerance） nature. To reliably diagnose food allergy, a careful history （immediate- type reactions） needs to be complemented with demonstration of specific IgE （immune mechanism） and confirmed by an oral challenge. Co-factors such as exercise, medication, and alcohol may help trigger food allergy and further complicate accurate diagnosis. Where food extract-based diagnostic tests are poorly correlated to symptom severity, new generation molecular diagnostics that measure IgE against individual food allergens provide clinicians and patients with more reliable symptom severity risk profiles. Molecular diagnostics also support establishing whether food sensitization originates directly from exposure to food or indirectly （cross-reactivity） from pollen sensitization. Epidemiological surveys have indicated that allergy to peach primarily originates from peach consumption in Europe, whereas in China it is the result of primary sensitization to mugwort pollen, in both cases mediated by an allergen molecule from the same family. Epidemiological surveys give insight into the etiology of food allergy, the size of the problem （prevalence）, and the risk factors involved, which together support evidence-based strategies for prevention. Over the past decade, food allergy has increased in the affluent world. Economic growth and urbanization in upcoming economies are likewise expected to lead to increased prevalence of food allergies, sometimes to different foods due to dietary habits. Molecular allergology and biotechnology now offer the possibility to combat the increasing burden of food allergy by developing safe immunotherapies for food allergy, using hypoallergenic mutant recombinant molecules. The first clinical trials to evaluate such approaches are underway. Last but not least, the identification and clinical risk characterization of a more and more complete list of food allergens additionally provides the allergenicity risk assessment of genetically modified foods a firmer basis.