Frevert U, Reinwald E
Institut für Veterinär-Biochemie, Freien Universität, Berlin-West, Federal Republic of Germany.
Eur J Cell Biol. 1990 Aug;52(2):264-9.
In the presence of antibodies against the variant surface glycoprotein (VSG) and guinea pig complement, Trypanosoma congolense bloodstream forms were lysed. Parasites, which had been preincubated with antibodies at 37 degrees C before addition of complement, escaped from complement lysis in a time- and temperature-dependent process. Preincubation caused removal of the antibodies from the cell surface by formation of filopodia and accumulation of the immune complexes between aggregated cells. Addition of secondary antibodies or of complement component C1q did not enhance this effect. In order to eliminate effects due to cell aggregation, single living trypanosomes, which had been immobilized by attachment to formvar-coated glass slides, were incubated under equivalent conditions. Immunofluorescence showed that in these experiments, anti-VSG antibodies were neither capped nor shed from the surface unless coincubation with secondary antibodies or C1q was performed. Fixation of the cells after incubation with anti-VSG prevented patching and capping of the antibodies. Removal of immune complexes apparently required no secondary cross-linker: removal from the surface of T. congolense obviously occurred during cell aggregation. This mechanism could therefore be of significance also in vivo.
在存在针对变异表面糖蛋白（VSG）的抗体和豚鼠补体的情况下，刚果锥虫血流型被裂解。在加入补体之前，已在37℃下与抗体预孵育的寄生虫，以时间和温度依赖性过程从补体裂解中逃脱。预孵育通过丝状伪足的形成以及聚集细胞之间免疫复合物的积累导致抗体从细胞表面去除。加入二抗或补体成分C1q并没有增强这种效果。为了消除细胞聚集的影响，将通过附着在福尔瓦包被的载玻片上而固定的单个活锥虫在相同条件下孵育。免疫荧光显示，在这些实验中，除非与二抗或C1q共同孵育，否则抗VSG抗体既不会从表面被封帽也不会脱落。用抗VSG孵育后固定细胞可防止抗体的斑块形成和封帽。免疫复合物的去除显然不需要二抗交联剂：从刚果锥虫表面的去除明显发生在细胞聚集过程中。因此，这种机制在体内也可能具有重要意义。
