Celada A, Schreiber R D
J Immunol. 1986 Oct 1;137(7):2373-9.
These studies were designed to test the hypothesis that changes in intracellular Ca2+ levels and activation of the calcium ion- and phospholipid-dependent protein kinase C were required for the induction of macrophage tumoricidal activity by interferon-gamma (IFN-gamma). Phenothiazines and R24571, known antagonists of calcium-binding proteins and therefore nonspecific inhibitors of protein kinase C, blocked in a dose-dependent manner the induction of macrophage cytocidal activity by either natural or recombinant IFN-gamma. Macrophages depleted of intracellular Ca2+ by chelation with Quin 2, were also unresponsive to IFN-gamma. These treatments effected neither the binding of IFN-gamma to its cell surface receptor nor the normal intracellular processing of IFN-gamma. Activators of protein kinase C (such as phorbol esters) and Ca2+ ionophores when added alone did not effect the activation state of the macrophage population. However, macrophages exposed to both drugs in combination were elevated into the primed activation state such that in the presence of a second signal (lipopolysaccharide or heat killed Listeria monocytogenes), the cells were triggered to express full levels of tumoricidal activity. The capacity of phorbol esters to induce cellular activation correlated with their ability to bind and to activate protein kinase C. No synergistic effect was observed between IFN-gamma and protein kinase C activators and/or Ca2+ ionophores, indicating that the drugs could only prime and could not trigger macrophages for tumor cell killing. These results thus support the concept that protein kinase C activation and mobilization of intracellular Ca2+ are essential steps in the pathway of IFN-gamma-dependent induction of non-specific tumoricidal activity in macrophages.
细胞内钙离子（Ca2+）水平的变化以及钙离子和磷脂依赖性蛋白激酶C的激活，是干扰素-γ（IFN-γ）诱导巨噬细胞杀肿瘤活性所必需的。吩噻嗪类药物和R24571是已知的钙结合蛋白拮抗剂，因此也是蛋白激酶C的非特异性抑制剂，它们以剂量依赖的方式阻断了天然或重组IFN-γ诱导的巨噬细胞杀细胞活性。用喹啉2螯合耗尽细胞内Ca2+的巨噬细胞，对IFN-γ也无反应。这些处理既不影响IFN-γ与其细胞表面受体的结合，也不影响IFN-γ正常的细胞内加工过程。单独添加蛋白激酶C激活剂（如佛波酯）和钙离子载体，不会影响巨噬细胞群体的激活状态。然而，同时暴露于这两种药物的巨噬细胞会被提升到预激活状态，这样在存在第二个信号（脂多糖或热灭活的单核细胞增生李斯特菌）时，细胞会被触发表达全部水平的杀肿瘤活性。佛波酯诱导细胞激活的能力与其结合和激活蛋白激酶C的能力相关。未观察到IFN-γ与蛋白激酶C激活剂和/或钙离子载体之间的协同作用，这表明这些药物只能使巨噬细胞致敏，而不能触发其杀伤肿瘤细胞。因此，这些结果支持了这样一种观点，即蛋白激酶C的激活和细胞内Ca2+的动员是IFN-γ依赖性诱导巨噬细胞非特异性杀肿瘤活性途径中的关键步骤。
