Liang Chengcheng, Sheng Xiuzhen, Tang Xiaoqian, Xing Jing, Chi Heng, Zhan Wenbin
Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Ocean University of China, 5 Yushan Road, Qingdao, 266003, PR China.
Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Ocean University of China, 5 Yushan Road, Qingdao, 266003, PR China.
Fish Shellfish Immunol. 2022 Apr;123:388-398. doi: 10.1016/j.fsi.2022.03.022. Epub 2022 Mar 21.
A specialized lymphoepithelial tissue termed the interbranchial lymphoid tissue (ILT) is recently identified in several fish species. However, the structural variation and mucosal immune functions of the ILT remain largely unknown. In this study, the anti-Zap-70 MAb was firstly determined to specifically recognize ZAP-70 protein, and CD4-1, CD4-2 and CD8β T-cells, but not IgM B cells, in peripheral blood leucocytes of flounder (Paralichthys olivaceus). Then we found that aggregates of Zap-70 cells were located in the epithelium covering the bottom of the interbranchial cleft and along the afferent and efferent edges of the filaments in a cross view, where a meshwork of epithelial cells containing diffused lymphoid cells was exhibited, confirming these structures as the ILT; In a sagittal view, Zap-70 cells were situated at the base of the filaments (here named as proximal ILT, pILT) and in the interlamellar epithelium (named as distal ILT, dILT). Also, a few IgM B cells were distributed at these sites. The lymphoepithelium within pILT and dILT was very thin with a low number of Zap-70 cells in premetamorphosis and postclimax larvae of flounder, and got thicker containing much more Zap-70 cells in juvenile and adult individuals. The aggregates of CD4-1/Zap-70, CD4-2/Zap-70, and CD8β/Zap-70 T-cell subsets were identified in the ILT. Post bath vaccination with inactivated Edwardsiella tarda and then intraperitoneal injection of EdU, the amounts of EdU and Zap-70 cells obviously increased at 3 d and 7 d, and co-localization of EdU/Zap-70 cells identified the presence of proliferative T cells; meanwhile, MHC class II-expressing cells were increased. These findings indicated that the ILT in gills of flounder was an important site for the induction of local T cell-mediated immunity, which would lead to a better understanding of mucosal immunity and defense mechanisms of teleost fish.
最近在几种鱼类中发现了一种特殊的淋巴上皮组织，称为鳃间淋巴组织（ILT）。然而，ILT的结构变异和黏膜免疫功能在很大程度上仍不清楚。在本研究中，首先确定抗Zap-70单克隆抗体能特异性识别牙鲆（Paralichthys olivaceus）外周血白细胞中的ZAP-70蛋白、CD4-1、CD4-2和CD8β T细胞，但不能识别IgM B细胞。然后我们发现，在鳃间裂底部的上皮以及鳃丝传入和传出边缘的横断面中，Zap-70细胞聚集，呈现出含有分散淋巴细胞的上皮细胞网络，证实这些结构为ILT；在矢状面中，Zap-70细胞位于鳃丝基部（此处称为近端ILT，pILT）和鳃小片间上皮（称为远端ILT，dILT）。此外，一些IgM B细胞也分布在这些部位。在牙鲆变态前和高潮后幼体中，pILT和dILT内的淋巴上皮非常薄，Zap-70细胞数量较少，而在幼鱼和成鱼个体中，淋巴上皮变厚，含有更多的Zap-70细胞。在ILT中鉴定出CD4-1/Zap-70、CD4-2/Zap-70和CD8β/Zap-70 T细胞亚群的聚集。用灭活迟缓爱德华氏菌进行浸浴免疫接种，然后腹腔注射EdU，在3天和7天时，EdU和Zap-70细胞的数量明显增加，EdU/Zap-70细胞的共定位确定了增殖T细胞的存在；同时，表达MHC II类分子的细胞增加。这些发现表明，牙鲆鳃中的ILT是诱导局部T细胞介导免疫的重要部位，这将有助于更好地理解硬骨鱼类的黏膜免疫和防御机制。
