Cytotoxic, or helper T cells recognize antigen via T cell receptors (TCRs) that can see their target antigen as short sequences of peptides bound to the groove of proteins of major histocompatibility complex (MHC) class I, and class II respectively. For MHC class II epitope selection from exogenous pathogens or self-antigens, participation of several accessory proteins, molecular chaperons, processing enzymes within multiple vesicular compartments is necessary. A major contributing factor is the MHC class II structure itself that uniquely offers a dynamic and flexible groove essential for epitope selection. In this review, I have taken a historical perspective focusing on the flexibility of the MHC II molecules as the driving force in determinant selection and interactions with the accessory molecules in antigen processing, HLA-DM and HLA-DO.

中文翻译：

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与主要组织相容性复合物 II 类和抗原决定簇合作需要灵活性和伴侣。

细胞毒性或辅助性 T 细胞通过 T 细胞受体 (TCR) 识别抗原，TCR 可以将其靶抗原视为分别与主要组织相容性复合物 (MHC) I 类和 II 类蛋白质凹槽结合的短肽序列。对于从外源性病原体或自身抗原中选择 MHC II 类表位，需要多个辅助蛋白、分子伴侣、多个囊泡区室中的加工酶的参与。一个主要的贡献因素是 MHC II 类结构本身，它独特地提供了一个动态和灵活的凹槽，对于表位选择至关重要。在这篇综述中，我从历史的角度关注 MHC II 分子的灵活性，作为决定性选择的驱动力，以及与抗原加工中的辅助分子 HLA-DM 和 HLA-DO 的相互作用。