Successful activation of CD4 T cells is centered around the ability of antigen presenting cells to successfully process, select Class II immunodominant epitopes from exogenous antigens and to present it to cognate T cells. To achieve this, newly synthesized MHC-II molecules are transferred to a specialized compartment which contain both exogenous antigens and the Class II processing machinery. Here in a process known as 'editing,' the Class II accessory molecule DM (HLA-DM human; murine H2-M) facilitates the loading and selection of exogenous peptides to MHC class II molecules thereby assuring proper selection of immunodominant epitopes. A second Class II accessory molecule, DO (HLA-DO human; murine H2-O), mainly present in B cells and thymic epithelium also contributes to the selection of immunodominant epitopes. Yet, despite a wealth of mechanistic insights into how DM functions, understanding the contributions of DO to epitope selection has proven to be highly challenging. In this review, we have attempted to discuss published in vitro and in vivo data during the past three years with insights into the biology of DO.

中文翻译：

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HLA-DM/DO在免疫优势表位选择中的爱恨关系。

CD4 T 细胞的成功激活以抗原呈递细胞成功处理、从外源抗原中选择 II 类免疫显性表位并将其呈递给同源 T 细胞的能力为中心。为了实现这一点，新合成的 MHC-II 分子被转移到包含外源抗原和 II 类加工机器的专门隔间中。在称为“编辑”的过程中，II 类辅助分子 DM（HLA-DM 人；鼠 H2-M）促进外源肽加载和选择到 MHC II 类分子，从而确保正确选择免疫显性表位。第二种 II 类辅助分子 DO（HLA-DO 人；鼠 H2-O）主要存在于 B 细胞和胸腺上皮中，也有助于选择免疫优势表位。然而，尽管对 DM 的功能有丰富的机制见解，但了解 DO 对表位选择的贡献已被证明是极具挑战性的。在这篇综述中，我们试图讨论过去三年中发表的体外和体内数据，并深入了解 DO 的生物学。