Tedesco F, Densen P, Villa M A, Presani G, Roncelli L, Rosso di san Secondo V E
Clin Exp Immunol. 1986 Nov;66(2):472-80.
Haemolytic assay for C8 revealed its association in functionally active form with washed human platelets. Platelet-bound C8 haemolytic activity was inhibited by F(ab')2 anti-C8 and was undetectable in the platelet suspension obtained from three C8 deficient patients. Incubation of platelets from C8 deficient individuals in normal plasma did not restore C8 haemolytic activity, indicating that platelets do not absorb C8 from plasma in vitro during platelet preparation. Thrombin, a mediator of the platelet release reaction, did not induce the release of C8 from normal platelets. Conversely, lysis of EAC1-7.9 by platelet bound C8 was not accompanied by release of beta-thromboglobulin or serotonin from the platelets. C8 was detected in a homogenate prepared from platelets as well as in the supernatant collected after high speed centrifugation of the homogenate. The association of C8 with platelets as an individual component rather than as part of the C5b-9 membrane-attack complex was supported by the following evidence: platelet bound C8 eluted from a Sephacryl S-200 column at the same volume as C8 from normal human serum; F(ab')2 anti-C8, but not F(ab')2 anti-C5, inhibited platelet C8 activity; the platelet homogenate, which lysed EAC1-7.9, had no effect on EAC43 which are susceptible to the lytic activity of the C5b-9 complex.
C8的溶血试验显示其以功能活性形式与洗涤后的人血小板相关联。血小板结合的C8溶血活性被F(ab')2抗C8抑制，并且在从三名C8缺陷患者获得的血小板悬液中未检测到。将C8缺陷个体的血小板在正常血浆中孵育并不能恢复C8溶血活性，这表明在血小板制备过程中，血小板在体外不会从血浆中吸收C8。凝血酶是血小板释放反应的介质，它不会诱导正常血小板释放C8。相反，血小板结合的C8对EAC1-7.9的裂解并未伴随着血小板中β-血小板球蛋白或5-羟色胺的释放。在由血小板制备的匀浆中以及在匀浆高速离心后收集的上清液中均检测到C8。以下证据支持C8作为单个成分而非作为C5b-9膜攻击复合物的一部分与血小板相关联：从Sephacryl S-200柱上洗脱的血小板结合C8与正常人血清中的C8洗脱体积相同；F(ab')2抗C8而非F(ab')2抗C5抑制血小板C8活性；能够裂解EAC1-7.9的血小板匀浆对易受C5b-9复合物裂解活性影响的EAC43没有作用。
