Schmidt R E, Caulfield J P, Michon J, Hein A, Kamada M M, MacDermott R P, Stevens R L, Ritz J
Division of Tumor Immunology, Dana-Farber Cancer Institute, Boston, MA 02115.
J Immunol. 1988 Feb 1;140(3):991-1002.
The T11 (CD2) antigen has been found to be an alternate pathway for antigen-independent activation of resting T cells. T11 triggering also results in activation of NK cells and enhancement of their cytolytic function. The present studies were carried out to further define the mechanisms whereby cytotoxicity is enhanced after T11 activation. A series of clonal human NK cell lines were analyzed after incubation with monoclonal anti-T112 and anti-T113 antibodies specific for different epitopes of the CD2 protein. Anti-T112/3 triggering resulted in increased cytotoxicity against a variety of target cells. Similar results were obtained with F(ab')2 fragments of anti-T112/3, indicating that this effect was not mediated through binding of FcR. The induction of cytotoxicity was found to be associated with increased formation of effector cell-target cell conjugates and with release of secretory granule-localized 35S-labeled proteoglycans. Both enhanced conjugate formation and cytotoxicity could be blocked by anti-lymphocyte function-associated antigen (LFA-1) mAb. Ultrastructural analysis of NK cells after T11 activation demonstrated increased adherence of effector cells to targets and other NK cells as well as a directional reorientation of cytoplasm and intracellular granules toward the area of contact between cells. Discharge of granules occurred into pockets bounded by closely apposed plasma membranes. In the presence of anti-LFA-1 and anti-T112/3, the close apposition and formation of pockets between effector cells and target cells did not occur but the cells exocytosed their intracellular granules. T11 activation of NK cloned cells also resulted in the formation of the homotypic conjugates and autocytotoxicity. As seen with resistant allogeneic targets, autocytotoxicity was mediated by F(ab')2 fragments of T112/3 antibodies and could be blocked by anti-LFA-1 antibody. Ultrastructural analysis of NK cloned cells after T11 activation confirmed the presence of homotypic conjugates with reorientation of effector cells toward one another and discharge of cytolytic granules into pockets formed between NK cloned cells. Taken together, these results indicate that T11-induced cytolytic function of NK cells is, in part, mediated through increased binding of effector cells and targets and that enhanced conjugate formation is at least in part mediated by the LFA-1 antigen. In addition, T11 activation results in the triggering of the cytolytic mechanism of NK cells and the exocytosis of cytolytic granules and their constituents.
已发现T11（CD2）抗原是静息T细胞非抗原依赖性激活的一条替代途径。T11触发还会导致NK细胞激活并增强其细胞溶解功能。开展本研究以进一步明确T11激活后细胞毒性增强的机制。在用针对CD2蛋白不同表位的单克隆抗T112和抗T113抗体孵育后，对一系列克隆化人NK细胞系进行了分析。抗T112/3触发导致对多种靶细胞的细胞毒性增加。用抗T112/3的F(ab')2片段也获得了类似结果，表明该效应不是通过FcR结合介导的。发现细胞毒性的诱导与效应细胞 - 靶细胞结合物形成增加以及分泌颗粒定位的35S标记蛋白聚糖的释放有关。增强的结合物形成和细胞毒性均可被抗淋巴细胞功能相关抗原（LFA - 1）单克隆抗体阻断。T11激活后NK细胞的超微结构分析显示，效应细胞与靶细胞以及其他NK细胞的黏附增加，并且细胞质和细胞内颗粒向细胞间接触区域定向重新定位。颗粒排放到由紧密并列的质膜界定的小袋中。在存在抗LFA - 1和抗T112/3的情况下，效应细胞与靶细胞之间不会发生紧密并列和小袋形成，但细胞会胞吐其细胞内颗粒。NK克隆细胞的T11激活还导致同型结合物形成和自身细胞毒性。如在抗性同种异体靶细胞中所见，自身细胞毒性由T112/3抗体的F(ab')2片段介导，并且可被抗LFA - 1抗体阻断。T11激活后NK克隆细胞的超微结构分析证实存在同型结合物，效应细胞彼此重新定向，并且溶细胞颗粒排放到NK克隆细胞之间形成的小袋中。综上所述，这些结果表明，T11诱导的NK细胞溶细胞功能部分是通过效应细胞与靶细胞结合增加介导的，并且增强的结合物形成至少部分由LFA - 1抗原介导。此外，T11激活导致NK细胞溶细胞机制的触发以及溶细胞颗粒及其成分的胞吐作用。
