Biancone L, David S, Della Pietra V, Montrucchio G, Cambi V, Camussi G
Cattedra di Nefrologia, Università di Parma, Italy.
Kidney Int. 1994 Feb;45(2):451-60. doi: 10.1038/ki.1994.59.
Human proximal tubular epithelial cells (PTEC) incubated with normal human serum (NHS) were found to fix on their surface C3, properdin, terminal complement components and C5b-9 MAC neoantigen, but not C1q and C4, by immunofluorescence. Complement fixation was abrogated if PTEC were incubated with EDTA-treated NHS or C3-deficient human serum, but not with Mg EGTA-treated NHS or C1q-deficient human serum, showing the prevalent activation of the alternative pathway of complement. This event was followed by marked cytoskeleton alterations with disruption of the actin cortical network, redistribution of actin throughout the cytoplasm and formation of blebs, and by cell cytolysis. In addition, superoxide anion and hydrogen peroxide production and chemiluminescence response were detected in consequence of MAC insertion on PTEC plasma membrane. The dependency on MAC of the observed biological effects of complement fixation on PTEC surface was shown by using sera selectively deficient of terminal components of complement (C6 or C8), and therefore unable to form the C5b-9 MAC, and by restoring the ability to form MAC after addition of purified C6 or C8. The possible pathogenetic relevance of these observations in tubulointerstitial injury occurring in patients with complementuria due to non-selective proteinuria, is discussed.
通过免疫荧光法发现，与正常人血清（NHS）孵育的人近端肾小管上皮细胞（PTEC）在其表面固定有C3、备解素、补体终末成分和C5b-9膜攻击复合物（MAC）新抗原，但未固定C1q和C4。如果将PTEC与经EDTA处理的NHS或C3缺陷型人血清孵育，补体固定作用会被消除，但与经Mg EGTA处理的NHS或C1q缺陷型人血清孵育则不会，这表明补体替代途径普遍激活。此事件之后是明显的细胞骨架改变，包括肌动蛋白皮质网络破坏、肌动蛋白在整个细胞质中重新分布以及形成泡状突起，随后细胞发生溶解。此外，由于MAC插入PTEC质膜，检测到超氧阴离子和过氧化氢生成以及化学发光反应。使用选择性缺乏补体终末成分（C6或C8）、因此无法形成C5b-9 MAC的血清，并在添加纯化的C6或C8后恢复形成MAC的能力，证明了补体固定在PTEC表面所观察到的生物学效应对MAC的依赖性。讨论了这些观察结果在因非选择性蛋白尿导致补体尿的患者发生肾小管间质损伤中可能的发病机制相关性。
