甲壳动物血细胞及其在免疫防御中的功能

Crustacean Haemocytes and Their Function in Immune Responses

甲壳动物的免疫反应主要依靠吞噬、包囊和凝集,属于非特异性免疫。血细胞在甲壳动物的免疫系统中具有重要作用。造血组织和造血干细胞为血细胞的生成、补充和更新提供了保障。血细胞成熟后分为不同类型,对血细胞分型的研究正在从采用传统的形态学方法向采用生物技术方法的方向发展,单克隆抗体技术已经应用于血细胞分型,结果更为客观准确。不同类型的血细胞在细胞化学特性与功能方面表现出明显差异。在甲壳动物的免疫反应中,血细胞数量在不同的免疫应激状态下发生明显变化。当外来病原体较小时,血细胞通过吞噬作用吞入病原体,在细胞内部将病原杀灭;而当入侵的病原体或寄生虫的个体大于10μm时则以多个血细胞的包囊作用或凝集作用来完成。甲壳动物的免疫反应是一个交互作用的复杂过程,必然涉及多层次、多个因子的参与。其中造血组织的结构,血细胞的产生及调控机理,采用单克隆抗体技术对血细胞进行分型标准的建立,免疫因子在免疫反应中的功能及它们之间的相互作用的网络关系等尚需深入研究。

Crustaceans have been shown to possess a primitive immune system that relies mainly on phagocytosis, encapsulation and agglutination. Haemocytes play important roles in crustacean immune responses. It is generally agreed that haematopoietic tissue （HPT） and haematopoietic stem cells are responsible for the production and supply of haemocytes. Most crustacean mature haemocytes were classified into three types by using light microscopy in the past few years. Recently, the monoclonal antibody technique has been used in identifying the types of some crustacean haemocytes, which was proved to be more accurate than classical methods. The cytochemical characteristics and function of different haemocyte subpopulations show significantly difference, suggesting a role for these cells in particular functions. It is demonstrated that total haemocyte counts （THC） changed obviously in crustacean immune response. Generally, the haemocytes defense action in crustaceans relies mainly on phagocytosis when the pathogen is very small, and the microorganism was killed in haemocytes. When a microorganism or parasite is bigger than 10μm, encapsulation and agglutination played a more important role. Moreover, the immune response of crustacean is very complex, during which cell co-operation and communication, and immune factors interaction are necessary. The study on the structure of HPT and the production mechanism of haemocytes, the establishment of classification standard of haemocyte subpopulations, the function and interaction of immune factors should be the main focus in the future.