The complement system represents an evolutionary old and critical component of innate immunity where it forms the first line of defense against invading pathogens. Originally described as a heat-labile fraction of the serum responsible for the opsonization and subsequent lytic killing of bacteria, work over the last century firmly established complement as a key mediator of the general inflammatory response but also as an acknowledged vital bridge between innate and adaptive immunity. However, recent studies particularly spanning the last decade have provided new insights into the novel modes and locations of complement activation and highlighted unexpected additional biological functions for this ancient system, for example, in regulating basic processes of the cell. In this review, we will cover the current knowledge about complement's established and novel roles in innate and adaptive immunity with a focus on the functional differences between serum circulating and intracellularly active complement and will describe and discuss the newly discovered cross-talks of complement with other cell effector systems particularly during T-cell induction and contraction.

中文翻译：

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补体驱动的免疫反应的“来龙去脉”。

补体系统代表了先天免疫的进化古老和关键组成部分，它形成了抵御入侵病原体的第一道防线。最初被描述为负责调理作用和随后溶解杀死细菌的血清中不耐热的部分，在上个世纪的工作中牢固确立了补体作为一般炎症反应的关键介质，同时也是先天性和适应性之间公认的重要桥梁免疫。然而，最近的研究，特别是过去十年的研究，为补体激活的新模式和位置​​提供了新的见解，并强调了这个古老系统意想不到的额外生物学功能，例如，在调节细胞的基本过程方面。在这篇评论中，我们将介绍有关补语的当前知识