Smyth M J, Norihisa Y, Ortaldo J R
Laboratory of Experimental Immunology, National Cancer Institute-Frederick Cancer Research and Development Center, MD 21702-1201.
J Immunol. 1992 Jan 1;148(1):55-62.
It has been proposed that CTL-mediated cytotoxicity may involve multiple lytic mechanisms. We have examined both the antibody-redirected cytolytic potential and the direct cytotoxicity of purified human peripheral blood high buoyant density CD4+ and CD8+ T cells activated with IL-2 and anti-CD3 mAb. TNF-sensitive and TNF-resistant targets and various metabolic inhibitors were used to compare the antibody-redirected cytotoxicity of T cell subsets and discern the role of potential lytic mediators. In a 4-h assay against several different nitrophenyl-modified targets, the heteroconjugated antibody (anti-CD3-anti-nitrophenyl) redirected cytolytic potential of 72-h activated CD4+ T cells was inhibited by the continuous presence of actinomycin D, cycloheximide, and EGTA, but not mitomycin C, cyclosporin A, or cholera toxin (CT). Conversely, only CT and EGTA inhibited the antibody-redirected cytolytic potential of activated CD8+ T cells. Despite both CD4+ and CD8+ T cell subsets expressing granzymes, pore-forming protein, TNF-beta, and TNF-alpha, these T cell subsets displayed distinct pathways of antibody-redirected lysis against TNF-sensitive and TNF-resistant targets, even in the presence of anti-TNF antibodies. In addition, these same effector T cell subsets were also directly cytotoxic (in the absence of heteroconjugated antibody) against TNF-sensitive targets in an 18-h assay. Indeed, this direct cytotoxicity was completely abrogated by anti-TNF-alpha antibody and was sensitive to the metabolic inhibitors (cyclosporin A, CT, cycloheximide, and actinomycin D), all of which blocked CD4+/CD8+ T cell TNF-alpha production. Therefore, both CD4+ and CD8+ T cells were demonstrated to utilize antibody and lymphokine-mediated lytic mechanisms. CD4+ and CD8+ effector subsets were demonstrated to lyse the same TNF-sensitive target by these two different mechanisms. Although it cannot be excluded that the redirected lytic mechanisms of both CD4+ and CD8+ effectors share common elements, it is likely that other important events in this cytolytic process are fundamentally distinct between these subsets of T cells.
有人提出，细胞毒性T淋巴细胞（CTL）介导的细胞毒性作用可能涉及多种溶解机制。我们研究了经白细胞介素-2（IL-2）和抗CD3单克隆抗体（mAb）激活的纯化人外周血高浮力密度CD4+和CD8+ T细胞的抗体重定向溶细胞潜能以及直接细胞毒性。使用对肿瘤坏死因子（TNF）敏感和耐药的靶细胞以及各种代谢抑制剂，来比较T细胞亚群的抗体重定向细胞毒性，并辨别潜在溶解介质的作用。在针对几种不同硝基苯基修饰靶细胞的4小时检测中，放线菌素D、环己酰亚胺和乙二醇双乙胺醚（EGTA）的持续存在会抑制72小时激活的CD4+ T细胞的异源缀合抗体（抗CD3-抗硝基苯基）重定向溶细胞潜能，但丝裂霉素C、环孢素A或霍乱毒素（CT）则不会。相反，只有CT和EGTA会抑制激活的CD8+ T细胞的抗体重定向溶细胞潜能。尽管CD4+和CD8+ T细胞亚群均表达颗粒酶、成孔蛋白、TNF-β和TNF-α，但即使存在抗TNF抗体，这些T细胞亚群针对TNF敏感和耐药靶细胞的抗体重定向裂解途径仍有所不同。此外，在18小时检测中，这些相同的效应T细胞亚群对TNF敏感靶细胞也具有直接细胞毒性（在不存在异源缀合抗体的情况下）。实际上，这种直接细胞毒性被抗TNF-α抗体完全消除，并且对代谢抑制剂（环孢素A、CT、环己酰亚胺和放线菌素D）敏感，所有这些抑制剂均会阻断CD4+/CD8+ T细胞TNF-α的产生。因此，已证明CD4+和CD8+ T细胞均利用抗体和淋巴因子介导的溶解机制。CD4+和CD8+效应亚群通过这两种不同机制裂解相同的TNF敏感靶细胞。尽管不能排除CD4+和CD8+效应细胞的重定向裂解机制具有共同要素，但在这个溶细胞过程中，其他重要事件在这些T细胞亚群之间可能存在根本差异。
