Conventional T cells recognise protein‐derived antigens in the context of major histocompatibility complex (MHC) class Ia and class II molecules and provide anti‐microbial and anti‐tumour immunity. Conventional T cells have also been implicated in type IV (also termed delayed‐type or T cell–mediated) hypersensitivity reactions in response to protein‐derived allergen antigens. In addition to conventional T cells, subsets of unconventional T cells exist, which recognise non‐protein antigens in the context of monomorphic MHC class I‐like molecules. These include T cells that are restricted to the cluster of differentiation 1 (CD1) family members, known as CD1‐restricted T cells, and mucosal‐associated invariant T cells (MAIT cells) that are restricted to the MHC‐related protein 1 (MR1). Compared with conventional T cells, much less is known about the immune functions of unconventional T cells and their role in hypersensitivities. Here, we review allergen antigen presentation by MHC‐I‐like molecules, their recognition by unconventional T cells, and the potential role of unconventional T cells in hypersensitivities. We also speculate on possible scenarios of allergen antigen presentation by MHC‐I‐like molecules to unconventional T cells, the hallmarks of such responses, and the expected frequencies of hypersensitivities within the human population.

中文翻译：

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非常规 T 细胞识别过敏原抗原后出现超敏反应


传统 T 细胞在主要组织相容性复合物 (MHC) Ia 类和 II 类分子的背景下识别蛋白质衍生的抗原，并提供抗微生物和抗肿瘤免疫。传统 T 细胞也涉及 IV 型（也称为迟发型或 T 细胞介导的）过敏反应，以响应蛋白质衍生的过敏原抗原。除了传统的 T 细胞之外，还存在非常规 T 细胞的子集，它们在单态 MHC I 类分子的背景下识别非蛋白质抗原。这些包括仅限于分化 1 (CD1) 家族成员簇的 T 细胞，称为 CD1 限制性 T 细胞，以及仅限于 MHC 相关蛋白 1 (MR1) 的粘膜相关不变 T 细胞 (MAIT 细胞) ）。与传统 T 细胞相比，人们对非常规 T 细胞的免疫功能及其在超敏反应中的作用知之甚少。在这里，我们回顾了 MHC-I 样分子的过敏原抗原呈递、非常规 T 细胞对它们的识别，以及非常规 T 细胞在超敏反应中的潜在作用。我们还推测 MHC-I 样分子向非常规 T 细胞呈递过敏原抗原的可能情况、此类反应的标志以及人群中超敏反应的预期频率。