Andersson Jonas, Ekdahl Kristina Nilsson, Lambris John D, Nilsson Bo
Department of Oncology, Radiology and Clinical Immunology, Section of Clinical Immunology, Rudbeck Laboratory C5, Uppsala University Hospital, SE-751 85 Uppsala, Sweden.
Biomaterials. 2005 May;26(13):1477-85. doi: 10.1016/j.biomaterials.2004.05.011.
In the present study we investigate whether complement activation in blood in contact with a model biomaterial surface (polystyrene) occurs directly on the material surface or on top of an adsorbed plasma protein layer. Quartz crystal microbalance-dissipation analysis (QCM-D) complemented with enzyme immunoassays and Western blotting were used. QCM-D showed that the surface was immediately covered with a plasma protein film of approximately 8 nm. Complement activation that started concomitantly with the adsorption of the protein film was triggered by a self-limiting classical pathway activation. After adsorption of the protein film, alternative pathway activation provided the bulk of the C3b deposition that added 25% more mass to the surface. The build up of alternative pathway convertase complexes using purified C3 and factors B and D on different protein films as monitored by QCM-D showed that only adsorbed albumin, IgG, but not fibrinogen, allowed C3b binding, convertase assembly and amplification. Western blotting of eluted proteins from the material surface demonstrated that the C3 fragments were covalently bound to other proteins. This is consistent with a model in which the activation is triggered by initiating convertases formed by means of the initially adsorbed proteins and the main C3b binding is mediated by the alternative pathway on top of the adsorbed protein film.
在本研究中，我们探究了与模型生物材料表面（聚苯乙烯）接触的血液中的补体激活是直接发生在材料表面，还是发生在吸附的血浆蛋白层之上。我们采用了石英晶体微天平耗散分析（QCM-D），并辅以酶免疫测定和蛋白质印迹法。QCM-D显示，表面立即被一层约8纳米的血浆蛋白膜覆盖。与蛋白质膜吸附同时开始的补体激活是由一种自我限制的经典途径激活引发的。蛋白质膜吸附后，替代途径激活导致了大部分C3b沉积，使表面质量增加了25%以上。通过QCM-D监测，在不同蛋白质膜上使用纯化的C3以及因子B和D构建替代途径转化酶复合物，结果表明只有吸附的白蛋白、IgG，而不是纤维蛋白原，允许C3b结合、转化酶组装和扩增。对从材料表面洗脱的蛋白质进行蛋白质印迹分析表明，C3片段与其他蛋白质共价结合。这与一个模型相符，即激活是由最初吸附的蛋白质形成的起始转化酶引发的，主要的C3b结合是由吸附的蛋白质膜之上的替代途径介导的。
