Biological Control of Insects Research Laboratory, USDA/Agricultural Research Service, Columbia, MO 65203, USA.
J Innate Immun. 2009;1(4):282-90. doi: 10.1159/000210371. Epub 2009 Mar 27.
Insects express 3 lines of protection from infections and invasions. Their cuticles and peritrophic membranes are physical barriers. Infections and invasions are quickly recognized within insect bodies, and recognition launches 2 lines of innate immune reactions. Humoral reactions involve induced synthesis of antimicrobial peptides, the bacteriolytic enzyme lysozyme and activation of the prophenoloxidase system. Cellular immune reactions include phagocytosis, nodulation and encapsulation. These reactions entail direct interactions between circulating hemocytes and the invaders. Cellular immune reactions begin immediately after an invasion is detected while antimicrobial peptides typically appear in the hemolymph some hours after infection. Microaggregation is a step in the nodulation process, which is responsible for clearing the bulk of bacterial infections from circulation. Coordinated cellular actions lead to encapsulation of invaders, such as parasitoid eggs, that are very much larger than individual hemocytes. In this paper, we review the roles of eicosanoids as central mediators of insect immune reactions, particularly cellular reactions. We briefly describe insect immune functions, outline eicosanoid biosynthesis and treat eicosanoid actions in cellular immunity of insects. Eicosanoids act in several cellular defense functions, including phagocytosis, microaggregation, nodulation, encapsulation, cell spreading and hemocyte migration toward a source of a bacterial peptide. We also describe our most recent work on the influence of one group of eicosanoids, prostaglandins, on gene expression in an established insect cell line.
昆虫有 3 条防线来抵御感染和入侵。它们的外骨骼和围食膜是物理屏障。昆虫体内的感染和入侵很快被识别，识别会引发 2 条先天免疫反应。体液反应包括诱导合成抗菌肽、溶菌酶和激活酚氧化酶原系统。细胞免疫反应包括吞噬作用、结节形成和包裹。这些反应涉及循环血细胞与入侵者之间的直接相互作用。细胞免疫反应在入侵被检测到后立即开始，而抗菌肽通常在感染后几个小时才出现在血液中。微聚集是结节形成过程中的一个步骤，它负责清除循环中大部分的细菌感染。协调的细胞作用导致对寄生虫卵等比单个血细胞大得多的入侵者的包裹。本文综述了类二十烷酸作为昆虫免疫反应，特别是细胞反应的重要介质的作用。我们简要描述了昆虫的免疫功能，概述了类二十烷酸的生物合成，并探讨了昆虫细胞免疫中的类二十烷酸作用。类二十烷酸在几种细胞防御功能中发挥作用，包括吞噬作用、微聚集、结节形成、包裹、细胞扩散和血细胞向细菌肽源的迁移。我们还描述了我们最近关于一组类二十烷酸——前列腺素对已建立的昆虫细胞系基因表达的影响的工作。
