Bhakdi S, Hugo F, Tranum-Jensen J
Institute of Medical Microbiology, University of Giessen, Federal Republic of Germany.
Blut. 1990 Jun;60(6):309-18. doi: 10.1007/BF01737843.
The terminal complement sequence is initiated upon cleavage of C5 with liberation of C5a anaphylatoxin, and involves the assembly of macromolecular C5b-9 complexes either on cell surfaces or in plasma. Cell-bound C5b-9 complexes generate transmembrane pores that can cause cell death, or they can elicit secondary cellular reactions triggered, for example, by passive flux of calcium ions into the cells. In vivo functions of the fluid-phase SC5b-9 complex have not yet been defined, but the identity of S-protein with vitronectin (serum spreading factor) provokes the anticipation that significant biological functions of this complex do exist. The terminal complement sequence may fulfil protective functions when it is triggered on alien cells that are marked for destruction. Dysregulation in the complement sequence may, however, result in detrimental attack by C5b-9 on autologous cells. Examples include not only autoimmune disease states, but also the activation of complement on dead or dying cells, and bystander attack on blood cells during cardiopulmonary bypass. Methods for detecting and quantifying C5b-9 are outlined, and the potential usefulness of such assays in clinical research is discussed.
补体终末序列在C5裂解并释放过敏毒素C5a时启动，涉及在细胞表面或血浆中组装大分子C5b-9复合物。细胞结合的C5b-9复合物会产生跨膜孔，可导致细胞死亡，或者引发继发性细胞反应，例如由钙离子被动流入细胞所触发的反应。液相SC5b-9复合物的体内功能尚未明确，但S蛋白与玻连蛋白（血清扩散因子）的一致性引发了人们对该复合物确实存在重要生物学功能的预期。当补体终末序列在外来细胞上触发时，可能发挥保护作用，这些外来细胞被标记以待破坏。然而，补体序列的失调可能导致C5b-9对自体细胞的有害攻击。例子不仅包括自身免疫疾病状态，还包括补体在死亡或濒死细胞上的激活，以及体外循环期间对血细胞的旁观者攻击。概述了检测和定量C5b-9的方法，并讨论了此类检测在临床研究中的潜在用途。
