Ting C C, Hargrove M E
Division of Cancer Biology and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Cell Immunol. 1991 Jul;135(2):273-84. doi: 10.1016/0008-8749(91)90273-e.
This study examines the role of cytokines in activating the effector cells to mediate slow lysis. After activation of splenocytes by alpha CD3, further culturing the cells in the absence of alpha CD3 resulted in the generation of activated killer cells (CD3-AK-) to mediate slow lysis. In contrast to fast lysis which was not affected by a PKC inhibitor H-7, slow lysis was inhibited. These findings suggested that a PKC-dependent activation phase preceded the lytic phase in slow lysis. To explore the mechanism for activating the lytic machinery in slow lysis, we examined the roles of cytokines in these reactions. First, it was found that alpha IL-2 or an alpha IL-2/alpha IL-4 combination inhibited slow lysis but had no effect on fast lysis. Secondly, IL-2, IL-4, or TNF alpha converted a noncytolytic CD3-AK- cells to mediate slow lysis, but they did not augment fast lysis. IL-2 and IL-4 had additive effect, and TNF alpha synergized with IL-2 to further augment the CD3-AK- cytolytic activity. Exogenous IL-6 and INF did not have any appreciable effect on the cytolytic activity of the killer cells. Besides TNF alpha, these cytokines were not directly cytotoxic to the target cells, indicating that they were not cytotoxic factors per se. Treatment with cycloheximide for 24 hr abrogated the cytolytic activities of CD3-AK cells, suggesting that a cytotoxic factor(s) was continuously synthesized to be stored in activated killer cells and was catabolized within 24 hr. Our results indicated that in the effector phase of slow lysis, after activating the CD3-AK- cells by the first signal (appropriate target cells), IL-2 and/or IL-4 appeared to be the second signal to initiate a cascade of events which triggered the release of other cytokines (e.g., TNF). This process resembles the secondary (memory) type of immune response. These events lead to full activation of the killer cells and converted the preformed cytotoxic factors into active form to initiate the lytic reaction and completed the lytic process.
本研究探讨细胞因子在激活效应细胞以介导缓慢裂解过程中的作用。用α-CD3激活脾细胞后，在无α-CD3的情况下进一步培养细胞，可产生激活的杀伤细胞（CD3-AK-）以介导缓慢裂解。与不受PKC抑制剂H-7影响的快速裂解相反，缓慢裂解受到抑制。这些发现表明，在缓慢裂解中，PKC依赖的激活阶段先于裂解阶段。为了探究缓慢裂解中激活裂解机制的作用，我们研究了细胞因子在这些反应中的作用。首先，发现α-IL-2或α-IL-2/α-IL-4组合可抑制缓慢裂解，但对快速裂解无影响。其次，IL-2、IL-4或TNF-α可使非细胞毒性的CD3-AK-细胞介导缓慢裂解，但它们不会增强快速裂解。IL-2和IL-4具有相加作用，TNF-α与IL-2协同作用可进一步增强CD3-AK-的细胞溶解活性。外源性IL-6和INF对杀伤细胞的细胞溶解活性没有明显影响。除TNF-α外，这些细胞因子本身对靶细胞无直接细胞毒性，表明它们本身不是细胞毒性因子。用放线菌酮处理24小时可消除CD3-AK细胞的细胞溶解活性，提示一种细胞毒性因子持续合成并储存于激活的杀伤细胞中，且在24小时内被分解代谢。我们的数据表明，在缓慢裂解的效应阶段，在通过第一信号（合适的靶细胞）激活CD3-AK-细胞后，IL-2和/或IL-4似乎是启动一系列事件的第二信号，这些事件触发了其他细胞因子（如TNF）的释放。这一过程类似于二次（记忆）型免疫反应。这些事件导致杀伤细胞完全激活，并将预先形成的细胞毒性因子转化为活性形式，从而启动裂解反应并完成裂解过程。
