Abstract：
As one of subunits for interleukin-2 receptor (IL-2R), CD122 can bind to IL-2 and then activate downstream signal transduction to participate in adaptive immune response. Although CD122 has been identified and investigated from several teleost species, studies on its function at T-cell level are still scarce for lack of specific antibodies. In this study, a typical CD122 in Nile tilapia (Oreochromis niloticus) was characterized by bioinformatics analysis, cloned to produce retrovirus infected NIH/3T3 cells for mouse immunization. After cell fusion and screening, we successfully developed a mouse anti-tilapia CD122 monoclonal antibody (mAb), which could specifically recognize CD122 and identify CD122-producing T cells of tilapia. Using the mAb to detect, CD122 was found to widely distribute in immune-related tissues, and significantly elevate post Edwardsiella piscicida infection or T-cell activation. More importantly, the expansion of CD122+ T cells and up-regulation of CD122 occurred both in total T cells and T-cell subsets during T-cell activation upon in vitro stimulation or in vivo infection. These results indicate that CD122 can be used as a T-cell activation marker in tilapia. Notably, CD122 mAb blocking blunted the activation of MAPK/Erk and mTORC1 pathways, and inhibited T-cell proliferation, suggesting a critical role of CD122 in ensuring proper proliferation of tilapia T cells. Therefore, this study enriches the knowledge of T-cell responses in fish and provides new evidence for understanding the evolution of lymphocyte-mediated adaptive immunity.
摘要：
作为白细胞介素-2受体（IL-2R）的亚基之一，CD122可以与IL-2结合，然后激活下游信号转导，参与适应性免疫应答。尽管已经从几种硬骨鱼物种中鉴定和研究了CD122，由于缺乏特异性抗体，在T细胞水平上对其功能的研究仍然很少。在这项研究中,通过生物信息学分析对尼罗罗非鱼（Oreochromisniloticus）中典型的CD122进行了表征，克隆产生逆转录病毒感染的NIH/3T3细胞用于小鼠免疫。经过细胞融合和筛选，成功研制出小鼠抗罗非鱼CD122单克隆抗体(mAb),它可以特异性识别CD122并鉴定罗非鱼的产生CD122的T细胞。用单克隆抗体检测，发现CD122广泛分布在免疫相关组织中，并在感染或T细胞活化后显著升高。更重要的是,在体外刺激或体内感染的T细胞激活过程中，总T细胞和T细胞亚群中CD122+T细胞的扩增和CD122的上调均发生。这些结果表明CD122可用作罗非鱼的T细胞活化标记。值得注意的是,CD122mAb阻断MAPK/Erk和mTORC1通路的激活,抑制T细胞增殖,提示CD122在确保罗非鱼T细胞正常增殖中的关键作用。因此,这项研究丰富了鱼类T细胞反应的知识，为理解淋巴细胞介导的适应性免疫的进化提供了新的证据。
