Puentes S M, Dwyer D M, Bates P A, Joiner K A
Clinical Immunology Section, National Institutes of Allergy and Infectious Diseases, Bethesda, MD 20892.
J Immunol. 1989 Dec 1;143(11):3743-9.
We have examined the nature and extent of C3 deposition on Leishmania donovani, strain 1S, clone 2D, promastigotes. Total molecules of C3 bound/parasite after 60 min was similar for parasites incubated in normal human serum, normal human serum adsorbed to remove natural antibody, or either serum source chelated with Mg-EGTA to limit activation to the alternative pathway. A comparison of parasites grown to early, mid, late-log or stationary phases revealed no difference in the extent and kinetics of C3 binding. C3 bound covalently to the parasite primarily through a hydroxylamine resistant (putatively amide) linkage. Of the bound C3, 75% was present as hemolytically inactive iC3b. Nearly 50% of the bound C3 was spontaneously released within 30 min at 37 degrees C. This spontaneous release was due to an unusual proteolytic cleavage event that released C3 from the C3 acceptor on the parasite surface. These results define and characterize the unusual features of C3 binding to L. donovani promastigotes during incubation in serum.
我们研究了补体C3在杜氏利什曼原虫1S株2D克隆前鞭毛体上沉积的性质和程度。在正常人类血清、吸附去除天然抗体的正常人类血清或用Mg-EGTA螯合以将激活限制在替代途径的任何一种血清来源中孵育60分钟后，每个寄生虫结合的C3总分子数相似。对生长至对数早期、中期、晚期或稳定期的寄生虫进行比较，结果显示C3结合的程度和动力学没有差异。C3主要通过耐羟胺（推测为酰胺）键与寄生虫共价结合。结合的C3中，75%以无溶血活性的iC3b形式存在。近50%结合的C3在37℃下30分钟内自发释放。这种自发释放是由于一种不寻常的蛋白水解切割事件，该事件将C3从寄生虫表面的C3受体上释放出来。这些结果定义并描述了血清孵育期间C3与杜氏利什曼原虫前鞭毛体结合的异常特征。
