Phagocytosis is a fundamental immune function against foreign microorganisms and abnormal cells, and it is also a bridge between innate and adaptive immunity. Blood as the direct living environment of various immune cells is a crucial site for phagocytosis. In this review, we firstly summarized the morphological structure and cytochemical characteristics of teleost peripheral blood cells, divided them into erythrocytes, leucocytes and thrombocytes, and then systematically elaborated the immune functions of phagocytic blood cells including professional and non-professional phagocytes. The professional phagocytes consist of monocytes/macrophages and neutrophils. Monocytes/macrophages activate phagocytosis to ingest pathogens, and destroy them through respiratory burst and nitric oxide response to generate antigens, and then antigens are presented to adaptive immune cells. Neutrophils are recruited to inflammatory sites and exert phagocytosis, which is accompanied by degranulation and the production of neutrophil extracellular traps to kill pathogens. Non-professional phagocytes including thrombocytes, B cells and erythrocytes are indispensable to exercise the phagocytosis, in addition to their main functions in the immune system. Thrombocytes participate in innate immunity and adaptive immunity. B cells carry out antigen presentation and immunoglobulin secretion in adaptive immunity. Erythrocytes perform immune regulation and infection resistance. In general, professional phagocytes play a primary role in phagocytosis and pathogen treatment, whereas non-professional phagocytes play auxiliary role in phagocytosis and perform their unique immune functions. The functions of these two types of phagocytes jointly constitute the basis of the immune system. This review provides insights into the overall roles of phagocytic blood cells in the teleost immune system.

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硬骨鱼吞噬血细胞的免疫功能

吞噬作用是抵抗外来微生物和异常细胞的基本免疫功能，也是先天免疫和适应性免疫之间的桥梁。血液作为各种免疫细胞的直接生存环境，是吞噬细胞的重要场所。本综述首先总结了硬骨鱼外周血细胞的形态结构和细胞化学特征，将其分为红细胞、白细胞和血小板，然后系统阐述了吞噬血细胞包括专业吞噬细胞和非专业吞噬细胞的免疫功能。专业吞噬细胞由单核细胞/巨噬细胞和中性粒细胞组成。单核细胞/巨噬细胞激活吞噬功能以摄取病原体，并通过呼吸爆发和一氧化氮反应破坏它们以产生抗原，然后将抗原呈递给适应性免疫细胞。中性粒细胞被招募到炎症部位并发挥吞噬作用，伴随着脱粒和中性粒细胞胞外陷阱的产生以杀死病原体。包括血小板、B细胞和红细胞在内的非专业吞噬细胞除了在免疫系统中的主要功能外，对于发挥吞噬作用也是必不可少的。血小板参与先天免疫和适应性免疫。B细胞在适应性免疫中进行抗原呈递和免疫球蛋白分泌。红细胞执行免疫调节和抗感染。一般来说，专业吞噬细胞在吞噬作用和病原体治疗中起主要作用，而非专业吞噬细胞在吞噬作用中起辅助作用并发挥其独特的免疫功能。这两种吞噬细胞的功能共同构成了免疫系统的基础。这篇综述提供了有关吞噬血细胞在硬骨鱼免疫系统中的整体作用的见解。