Gibboney J J, Shenoy A M, Jin X, Brahmi Z
Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis 46202-5200.
Nat Immun. 1992 Mar-Apr;11(2):57-68.
We have recently demonstrated that the activation of NK cells involves a protein-kinase-C (PKC)-dependent step as well as a phosphatidylinositol (PI)-linked signal transduction system. We have also shown that when NK cells are incubated with sensitive targets for up to 6 h they lose their lytic potential and require IL-2 to regain their lytic activity. PKC is involved in many cell processes such as the transduction of hormonal signals and the machinery of cellular secretion and is activated by diacylglycerol and by a number of phorbol esters, including phorbol myristic acid (PMA). To reinforce the role of PKC in NK-cell-mediated cytotoxicity, we first showed that NK-CMC is inhibited by two agents that inhibit PKC activation, staurosporine and sphingosine. Next, we showed that antibody-dependent cellular cytotoxicity of NK-resistant targets was PKC dependent and Ca2+ dependent. Further, we showed that PMA plus ionophore alone could induce NK killing of resistant targets and that this killing was PKC and Ca2+ dependent. Finally, we contrasted the role of PKC in these activated cells to the role of PKC in cells that have been inactivated with a sensitive target, K562. We showed that PKC is not required for the IL-2-dependent reactivation of NK cells but that Ca2+ is required. To further determine what event in signal transduction is inactivated by K562, we showed that inactivated NK cells do not turnover PI in response to K562 stimulation.
我们最近证明，自然杀伤细胞（NK细胞）的激活涉及一个蛋白激酶C（PKC）依赖性步骤以及一个磷脂酰肌醇（PI）连接的信号转导系统。我们还表明，当NK细胞与敏感靶细胞孵育长达6小时时，它们会失去裂解潜力，需要白细胞介素-2（IL-2）才能恢复其裂解活性。PKC参与许多细胞过程，如激素信号转导和细胞分泌机制，并被二酰基甘油和多种佛波酯激活，包括佛波醇肉豆蔻酸酯（PMA）。为了强化PKC在NK细胞介导的细胞毒性中的作用，我们首先表明，NK细胞介导的细胞毒性（NK-CMC）受到两种抑制PKC激活的药物——星形孢菌素和鞘氨醇的抑制。接下来，我们表明，NK抗性靶细胞的抗体依赖性细胞毒性是PKC依赖性和Ca2+依赖性的。此外，我们表明，单独的PMA加离子载体可以诱导NK细胞杀伤抗性靶细胞，并且这种杀伤是PKC和Ca2+依赖性的。最后，我们对比了PKC在这些活化细胞中的作用与PKC在已被敏感靶细胞K562灭活的细胞中的作用。我们表明，NK细胞的IL-2依赖性再激活不需要PKC，但需要Ca2+。为了进一步确定信号转导中的什么事件被K562灭活，我们表明，灭活的NK细胞在受到K562刺激时不会周转PI。
