Wang Weilin, Li Meijia, Wang Lingling, Chen Hao, Liu Zhaoqun, Jia Zhihao, Qiu Limei, Song Linsheng
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, China.
Dev Comp Immunol. 2017 Feb;67:221-228. doi: 10.1016/j.dci.2016.09.017. Epub 2016 Sep 28.
Hemocytes comprise diverse cell types with morphological and functional heterogeneity and play indispensable roles in immunological homeostasis of invertebrates. The morphological classification of different hemocytes in mollusk has been studied since the 1970's, yet the involvement of the different sub-populations in immune functions is far from clear. In the present study, three types of hemocytes were morphologically identified and separated as agranulocytes, semi-granulocytes and granulocytes by flow cytometry and Percoll density gradient centrifugation. The granulocytes were characterized functionally as the main phagocytic and encapsulating population, while semi-granulocytes and agranulocytes exhibited low or no such capacities, respectively. Meanwhile, the lysosome activity and the productions of ROS and NO were all mainly concentrated in granulocytes under both normal and immune-activated situations. Further, the mRNA transcripts of some immune related genes, including CgTLR, CgClathrin, CgATPeV, CgLysozyme, CgDefensin and CgIL-17, were mainly expressed in granulocytes, lower in semi-granulocytes and agranulocytes. These results collectively suggested that the granulocytes were the main immunocompetent hemocytes in oyster C. gigas, and a differentiation relationship among these three sub-population hemocytes was inferred based on the gradual changes in morphological, functional and molecular features.
血细胞由具有形态和功能异质性的多种细胞类型组成，在无脊椎动物的免疫稳态中发挥着不可或缺的作用。自20世纪70年代以来，人们一直在研究软体动物中不同血细胞的形态分类，但不同亚群在免疫功能中的作用仍远未明确。在本研究中，通过流式细胞术和Percoll密度梯度离心法从形态上鉴定并分离出三种血细胞，即无颗粒细胞、半颗粒细胞和颗粒细胞。颗粒细胞在功能上被表征为主要的吞噬和包囊细胞群，而半颗粒细胞和无颗粒细胞分别表现出低或无此类能力。同时，在正常和免疫激活情况下，溶酶体活性、活性氧（ROS）和一氧化氮（NO）的产生都主要集中在颗粒细胞中。此外，一些免疫相关基因的mRNA转录本，包括CgTLR、CgClathrin、CgATPeV、CgLysozyme、CgDefensin和CgIL-17，主要在颗粒细胞中表达，在半颗粒细胞和无颗粒细胞中表达较低。这些结果共同表明，颗粒细胞是长牡蛎中主要的免疫活性血细胞，并根据这三个亚群血细胞在形态、功能和分子特征上的逐渐变化推断出它们之间的分化关系。
