Abstract

The complement system is the human’s first line of defense against microbial pathogens because of its important housekeeping and infection/inflammation roles. It is composed of a series of soluble and cell-bound proteins that are activated in a cascade effect, similar to the coagulation pathways. There are different pattern recognizing molecules that activate the complement system in response to stimuli or threats, acting through three initiation pathways: classical, lectin, and alternative. All three activation pathways converge at the C3 component and share the terminal pathway. The main outputs of the complement system action are lytic killing of microbes, the release of pro-inflammatory anaphylatoxins, and opsonization of targets. Laboratory testing is relevant in the setting of suspected complement deficiencies, as well as in the emerging number of diseases related to dysregulation (over-activation) of complement. Most common assays measure complement lytic activity and the different complement component concentrations. Specialized testing includes the evaluation of autoantibodies against complement components, activation fragments, and genetic studies. In this review, we cover laboratory testing for complement and the conditions with complement involvement, as well as current challenges in the field.

摘要

补体系统是人类抵御微生物病原体的第一道防线，因为它具有重要的看家和感染/炎症作用。它由一系列可溶的和细胞结合的蛋白质组成，这些蛋白质以级联效应被激活，类似于凝血途径。有不同的模式识别分子可激活补体系统以响应刺激或威胁，通过三种起始途径起作用：经典、凝集素和替代。所有三个激活途径都汇聚在 C3 组件处并共享终端途径。补体系统作用的主要输出是微生物的裂解杀死、促炎性过敏毒素的释放和靶标的调理作用。实验室检测与怀疑补体缺乏相关，以及与补体失调（过度激活）相关的新出现的疾病数量。最常见的测定测量补体裂解活性和不同的补体成分浓度。专业测试包括评估针对补体成分的自身抗体、激活片段和遗传研究。在这篇综述中，我们涵盖了补体的实验室检测和补体参与的条件，以及该领域当前的挑战。