MacKay S L, Dankert J R
Department of Comparative and Experimental Pathology, University of Florida, Gainesville 32610.
J Immunol. 1990 Nov 15;145(10):3367-71.
The assembly of the C5b-9 complex on the outer membrane of C-sensitive cells of Escherichia coli results in a rapid inhibition of inner membrane function and ultimately a loss of cell viability. Cells bearing C5b-8 sites suffer no deleterious effects; however, the addition of C9 results in a rapid inhibition of inner membrane function and cell death. An attempt was made to examine the relationship between the toxic effects of the C5b-9 complex and the number of C9 molecules per C5b-8 site. Cells bearing C5b-8 sites were exposed to excess C9 at 0 degrees C and washed three times at 4 degrees C. The number of C9 molecules bound to each cell was equivalent to the number of C5b-8 sites present on each cell, and no additional C9 molecules could be bound when the cells were maintained at 4 degrees C. These cells were then incubated at 37 degrees C for 3 min and returned to 0 degrees C, a technique which exposed additional C9-binding sites equivalent to the number of C9 molecules previously bound to the cells. This technique was repeated and demonstrated that the sequential build-up of a C5b-9 site with two C9 molecules per C5b-8 site was capable of inhibiting both inner membrane function (respiration and amino acid transport) and cell viability. Three C9 molecules per complex had effects that approached the inhibitory effects of complexes formed in the presence of excess C9.
C5b-9复合物在大肠杆菌C敏感细胞的外膜上组装，会迅速抑制内膜功能，最终导致细胞活力丧失。带有C5b-8位点的细胞没有受到有害影响；然而，添加C9会迅速抑制内膜功能并导致细胞死亡。我们试图研究C5b-9复合物的毒性作用与每个C5b-8位点C9分子数量之间的关系。将带有C5b-8位点的细胞在0℃下暴露于过量的C9，并在4℃下洗涤三次。每个细胞结合的C9分子数量与每个细胞上存在的C5b-8位点数量相当，当细胞维持在4℃时，没有额外的C9分子能够结合。然后将这些细胞在37℃下孵育3分钟，再回到0℃，该技术暴露了与先前结合到细胞上的C9分子数量相当的额外C9结合位点。重复该技术，结果表明，每个C5b-8位点有两个C9分子的C5b-9位点的顺序积累能够抑制内膜功能（呼吸作用和氨基酸转运）以及细胞活力。每个复合物有三个C9分子的作用接近在过量C9存在下形成的复合物的抑制作用。
