Shearer W T, Moore E G
Res Commun Chem Pathol Pharmacol. 1984 Aug;45(2):163-78.
The nature of C3 binding to cell surfaces was examined in L cells treated with antibody and complement, immunological reagents which we have previously shown to be capable of producing stimulation of several important cellular processes. In the presence of serums containing C3 and under experimental conditions where complement activation could take place, selective binding of C3 to antibody treated L cells was observed (maximum 1.1 X 10(6) C3 molecules per cell). Under similar conditions there was a C3 dependent increased calcium uptake (3.4 pmol) by antibody treated cells. Purified C3 was able to selectively restore C3 binding to cells treated with serum depleted of C3 through C9. C7-deficient serum was almost as good a source of activated C3 as its normal serum counterpart. Strong chemical nucleophiles such as salicylhydroxamic acid, which are capable of covalently coupling to the labile internal thiolester of C3, prevented the binding of C3 to cells. We conclude that C3 is covalently bound to antibody and complement treated L cells, possibly serving as an important signal in subsequent enhancement of phospholipid metabolism, DNA synthesis, and cell growth.
在经抗体和补体处理的L细胞中研究了C3与细胞表面结合的性质，我们之前已证明这些免疫试剂能够刺激多种重要的细胞过程。在含有C3的血清存在下，以及在能够发生补体激活的实验条件下，观察到C3选择性地结合至经抗体处理的L细胞（每个细胞最多1.1×10⁶个C3分子）。在类似条件下，经抗体处理的细胞存在C3依赖性的钙摄取增加（3.4皮摩尔）。纯化的C3能够选择性地恢复C3与经C3至C9缺失血清处理的细胞的结合。C7缺陷血清作为活化C3的来源，几乎与正常血清相当。强化学亲核试剂如水杨基异羟肟酸，能够与C3不稳定的内部硫酯共价偶联，可阻止C3与细胞的结合。我们得出结论，C3与经抗体和补体处理的L细胞共价结合，可能在随后增强磷脂代谢、DNA合成和细胞生长过程中作为重要信号。
