Kupfer A, Dennert G, Singer S J
Department of Biology, University of California, San Diego, La Jolla 92037.
J Mol Cell Immunol. 1985;2(1):37-49.
This investigation is concerned with the detailed mechanisms of cytotoxicity, and in particular, with early cell surface and intracellular events that occur upon the binding of a cytotoxic effector cell to its susceptible target. In earlier studies, we have shown by immunofluorescence microscopy that when cloned natural killer (NK) and cytolytic T lymphocyte (CTL) cells bind to susceptible target cells, a rapid and coordinate reorientation of the perinuclear Golgi apparatus and the microtubule-organizing center (MTOC) occurs inside the effector cell so that the two organelles face the bound target. It was proposed that the purpose served by this reorientation is to direct Golgi-derived secretory vesicles, containing one or more cytotoxic components, to the area of target cell binding. In order to establish more firmly that this reorientation of the two organelles is an essential early event in cytotoxicity, we have performed three different types of experiments. 1) Upon binding cloned effector cells to susceptible targets in the presence of Mg+2 but absence of Ca+2, conditions in which no killing occurs, we found that no reorientation of the MTOC in the effector cell is induced; however, the addition of CA+2 to these cell couples results in a rapid MTOC reorientation. 2) With a lysis-defective subclone derived from a cytolytic NK clone, binding to target cells did not induce an MTOC reorientation in the defective killer cell. 3) In multitarget conjugates formed with single CTL, the MTOC in the CTL was oriented to face that one target cell which was in the process of lysis at the time. These results, together with our earlier findings, strongly indicate that a Golgi/MTOC reorientation inside the target-bound effector cell is a pre-requisite for the effective lysis of the target. They also reveal the existence, previously unrecognized, of a specific signaling mechanism from the viable target cell to the effector cell, which must be involved in the triggering of this Golgi/MTOC reorientation. These conclusions are consistent with the proposal that a polar cytotoxic secretory mechanism is responsible for target cell lysis.
本研究关注细胞毒性的详细机制，特别是细胞毒性效应细胞与其敏感靶细胞结合后早期细胞表面和细胞内发生的事件。在早期研究中，我们通过免疫荧光显微镜观察发现，当克隆的自然杀伤（NK）细胞和细胞毒性T淋巴细胞（CTL）与敏感靶细胞结合时，效应细胞内的核周高尔基体和微管组织中心（MTOC）会迅速且协调地重新定向，使这两个细胞器面向结合的靶细胞。有人提出，这种重新定向的目的是将含有一种或多种细胞毒性成分的高尔基体衍生分泌囊泡导向靶细胞结合区域。为了更确切地确定这两个细胞器的重新定向是细胞毒性早期的关键事件，我们进行了三种不同类型的实验。1）在存在Mg+2但不存在Ca+2的情况下，将克隆的效应细胞与敏感靶细胞结合，此时不会发生杀伤，我们发现效应细胞中的MTOC不会被诱导重新定向；然而，向这些细胞对中添加Ca+2会导致MTOC迅速重新定向。2）用源自细胞毒性NK克隆的裂解缺陷亚克隆与靶细胞结合，在缺陷杀伤细胞中不会诱导MTOC重新定向。3）在由单个CTL形成的多靶细胞结合物中，CTL中的MTOC定向于当时正在被裂解的那个靶细胞。这些结果与我们早期的发现一起，有力地表明靶细胞结合的效应细胞内高尔基体/MTOC重新定向是有效裂解靶细胞的先决条件。它们还揭示了以前未被认识到的从存活靶细胞到效应细胞的特定信号传导机制的存在，该机制必定参与了这种高尔基体/MTOC重新定向的触发。这些结论与极性细胞毒性分泌机制负责靶细胞裂解的提议一致。
