The mucosal immune system of the respiratory tract is specialized to continuously monitor the external environment and to protect against invading pathogens, while maintaining tolerance to innocuous inhaled particles. Allergies result from a loss of tolerance against harmless antigens characterized by formation of allergen-specific Th2 cells and IgE. Tolerance is often described as a balance between harmful Th2 cells and various types of protective "regulatory" T cells. However, the identity of the protective T cells in healthy vs. allergic individuals or following successful allergen-specific therapy is controversially discussed. Recent technological progress enabling the identification of antigen-specific effector and regulatory T cells has significantly contributed to our understanding of tolerance. Here we discuss the experimental evidence for the various tolerance mechanisms described. We try to integrate the partially contradictory data into a new model proposing different mechanism of tolerance depending on the quality and quantity of the antigens as well as the way of antigen exposure. Understanding the basis of tolerance is essential for the rational design of novel and more efficient immunotherapies.

中文翻译：

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针对空气抗原的抗原特异性调节性 T 细胞反应及其在过敏中的作用。

呼吸道的粘膜免疫系统专门用于持续监测外部环境并防止入侵的病原体，同时保持对无害吸入颗粒的耐受性。过敏是由于对无害抗原的耐受性丧失所致，其特征是过敏原特异性 Th2 细胞和 IgE 的形成。耐受性通常被描述为有害的 Th2 细胞和各种类型的保护性“调节性”T 细胞之间的平衡。然而，保护性 T 细胞在健康个体与过敏个体或成功的过敏原特异性治疗后的特性存在争议。最近的技术进步能够识别抗原特异性效应细胞和调节性 T 细胞，这极大地促进了我们对耐受性的理解。在这里，我们讨论了所描述的各种耐受机制的实验证据。我们试图将部分矛盾的数据整合到一个新模型中，根据抗原的质量和数量以及抗原暴露的方式提出不同的耐受机制。了解耐受性的基础对于合理设计新颖且更有效的免疫疗法至关重要。