Wright S D, Levine R P
J Immunol. 1981 Sep;127(3):1152-6.
We have studied the nature of complement (C) action on red blood cells and E. coli with respect to the number of "hits" required for membrane damage. Our method of analysis involves adding various amounts of purified C7 or C8 to serum preparations immunochemically depleted of C7 or C8, respectively, in order to construct dose-response curves for the action of C's terminal complex. The shape of the dose-response curves reflects the single or multiple-hit nature of C action. Our method confirms that C acts on red cells by a 1-hit mechanism, whether measured by lysis or by the permeation of a small molecule. In contrast, we find with E. coli that C-mediated outer membrane damage, inner membrane damage, and killing all appear to require more than 1 hit. We have also discovered a property of E. coli that displays a nonlethal 1-hit response to C that is particularly useful in the analysis of multiple-hit dose-response curves. Simultaneous measurements of this single-hit phenomenon and the multiple-hit killing of E. coli allow us to make direct comparisons of the amount of C needed for each response. On the basis of the midpoints of the single and multiple-hit curves, C-mediated membrane damage and killing of E. coli appear to be a 2-hit process.
我们研究了补体（C）对红细胞和大肠杆菌的作用性质，涉及膜损伤所需的“命中”次数。我们的分析方法包括分别向免疫化学去除C7或C8的血清制剂中添加不同量的纯化C7或C8，以构建补体末端复合物作用的剂量反应曲线。剂量反应曲线的形状反映了补体作用的单次或多次命中性质。我们的方法证实，无论通过裂解还是小分子渗透来测量，补体对红细胞的作用都是通过单次命中机制。相比之下，我们发现对于大肠杆菌，补体介导的外膜损伤、内膜损伤和杀伤似乎都需要多次命中。我们还发现了大肠杆菌的一种特性，即对补体表现出非致死性的单次命中反应，这在多次命中剂量反应曲线的分析中特别有用。同时测量这种单次命中现象和大肠杆菌的多次命中杀伤，使我们能够直接比较每种反应所需的补体量。根据单次和多次命中曲线的中点，补体介导的大肠杆菌膜损伤和杀伤似乎是一个两次命中的过程。
