Anthony L S, Morrissey P J, Nano F E
Department of Biochemistry and Microbiology, University of Victoria, British Columbia.
J Immunol. 1992 Mar 15;148(6):1829-34.
We have examined the abilities of the recombinant murine lymphokines IFN-gamma, granulocyte-macrophage (GM)-CSF, and IL-4 to stimulate the in vitro antimicrobial activity of macrophages against the live vaccine strain (LVS) of Francisella tularensis. Resident peritoneal macrophages from C57BL/6 strain mice were cultured overnight with IFN-gamma, GM-CSF, or IL-4, and then infected with LVS. In macrophages treated with IFN-gamma, the growth of LVS was suppressed by a factor of 100- to 1000-fold in comparison with untreated cells. This effect was dose-dependent and was enhanced by the addition of LPS. In contrast, macrophages treated with either GM-CSF or IL-4 exhibited no such enhanced antitularemic activity, even in the presence of LPS. Because reactive nitrogen intermediates derived from L-arginine metabolism have been implicated in the killing of various infectious organisms, we evaluated the possibility that such a mechanism might contribute to the antitularemic activity of IFN-gamma-stimulated macrophages. Macrophages were treated with NG-monomethyl-L-arginine (NMMA), an inhibitor of L-arginine metabolism in mammalian cells, during the activation procedure and throughout the course of infection. NMMA had no effect on the growth of LVS in unstimulated macrophages. In macrophages activated with IFN-gamma, however, NMMA suppressed their capacity to inhibit LVS growth. This effect was proportional to the dose of NMMA added and reversible by supplementing the medium with additional L-arginine, and there was a direct correlation between the production of nitrite by activated macrophages and their ability to inhibit LVS growth. Furthermore, the growth of LVS was inhibited by nitrogen metabolites in a cellfree system. The results of this study indicate that the mechanism of action of IFN-gamma on the resistance of macrophages to LVS growth is related, at least in part, to the production of reactive nitrogen metabolites.
我们研究了重组鼠源淋巴因子γ干扰素（IFN-γ）、粒细胞-巨噬细胞集落刺激因子（GM-CSF）和白细胞介素-4（IL-4）刺激巨噬细胞对土拉弗朗西斯菌活疫苗株（LVS）体外抗菌活性的能力。将C57BL/6品系小鼠的腹腔常驻巨噬细胞与IFN-γ、GM-CSF或IL-4一起培养过夜，然后用LVS感染。在用IFN-γ处理的巨噬细胞中，与未处理的细胞相比，LVS的生长被抑制了100至1000倍。这种效应呈剂量依赖性，并且通过添加脂多糖（LPS）而增强。相比之下，用GM-CSF或IL-4处理的巨噬细胞即使在存在LPS的情况下也没有表现出这种增强的抗土拉菌活性。由于L-精氨酸代谢产生的反应性氮中间体与杀死各种感染性生物体有关，我们评估了这种机制可能有助于IFN-γ刺激的巨噬细胞的抗土拉菌活性的可能性。在激活过程中和整个感染过程中，用NG-单甲基-L-精氨酸（NMMA）处理巨噬细胞，NMMA是哺乳动物细胞中L-精氨酸代谢的抑制剂。NMMA对未刺激的巨噬细胞中LVS的生长没有影响。然而，在用IFN-γ激活的巨噬细胞中，NMMA抑制了它们抑制LVS生长的能力。这种效应与添加的NMMA剂量成比例，并且通过在培养基中补充额外的L-精氨酸可逆转，并且激活的巨噬细胞产生亚硝酸盐与其抑制LVS生长的能力之间存在直接相关性。此外，在无细胞系统中，LVS的生长被氮代谢产物抑制。本研究结果表明，IFN-γ对巨噬细胞抵抗LVS生长的作用机制至少部分与反应性氮代谢产物的产生有关。
