Pfefferkorn L C, Guyre P M, Fanger M W
Department of Microbiology, Dartmouth Medical School, Hanover, NH 03756.
Mol Immunol. 1990 Mar;27(3):263-72. doi: 10.1016/0161-5890(90)90139-q.
The capacity to generate superoxide anion (O2-) can be induced in U937 cells by various agents known to cause myeloid cell differentiation. Other reported differentiation events include diminished cell proliferation and the induction by gamma-interferon (IFN gamma) of Fc receptors for immunoglobulin G1 (Fc gamma RI). In this study, we differentiated U937 cells and high Fc gamma RI-expression mutants of U937 cells by treating them with IFN gamma. We compared the time courses over which surface Fc gamma RI became maximal, NADPH oxidase activity was induced, and the antiproliferative effect of IFN gamma was detected. Oxidase activity was measured by stimulating cells with PMA or by activating surface Fc gamma RI using aggregated human IgG1 or second antibody crosslinking of mAb 32/Fc gamma RI complexes. We found that IFN gamma in the absence of additional lymphokines induced high levels of oxidase activity in maximally differentiated U937 cells with even higher levels in the fully differentiated high-Fc gamma RI expression mutants (greater than 8 nmoles/10(6) cells/min for A12.13 cells). Over the course of differentiation, maximal induced levels of Fc gamma RI were reached after 1 to 2 days of IFN gamma treatment, prior to the antiproliferative effect of the lymphokine. In contrast, oxidase activity was induced after a lag of approximately 2 days, becoming maximal only after 4 to 6 days of IFN gamma treatment. This comparison of the induction of Fc gamma RI with that of oxidase activity triggered through Fc gamma RI indicated that the rapid increase of surface receptor was not accompanied by a completion of the pathway of Fc gamma RI-mediated oxidase activity. However, the time courses of induction detected by PMA and Fc gamma RI-agonists were coincident suggesting that the development of oxidative capacity could be due to the induction of components required by both the PMA- and surface receptor-mediated pathways. There are several oxidase components that are known to be IFN gamma-inducible, such as the oxidase flavoprotein, a b558 cytochrome peptide, and oxidase-requiring cytosolic components, and it is possible that one or a set of these components could be the limiting factor(s) for IFN gamma-induced oxidase activity.
多种已知可诱导髓样细胞分化的因子能使U937细胞产生超氧阴离子（O2-）的能力增强。其他已报道的分化事件包括细胞增殖减少以及γ干扰素（IFNγ）诱导免疫球蛋白G1的Fc受体（FcγRI）。在本研究中，我们通过用IFNγ处理U937细胞及其高FcγRI表达突变体来使其分化。我们比较了表面FcγRI达到最大值、诱导NADPH氧化酶活性以及检测IFNγ的抗增殖作用的时间进程。通过用佛波酯（PMA）刺激细胞或使用人IgG1聚集物或单克隆抗体32/FcγRI复合物的二抗交联来激活表面FcγRI，从而测定氧化酶活性。我们发现，在没有其他细胞因子的情况下，IFNγ能在高度分化的U937细胞中诱导高水平的氧化酶活性，而在完全分化的高FcγRI表达突变体中水平更高（A12.13细胞大于8纳摩尔/10^6个细胞/分钟）。在分化过程中，IFNγ处理1至2天后达到FcγRI的最大诱导水平，早于该细胞因子的抗增殖作用。相比之下，氧化酶活性在约2天的延迟后被诱导，仅在IFNγ处理4至6天后才达到最大值。将FcγRI的诱导与通过FcγRI触发的氧化酶活性的诱导进行比较表明，表面受体的快速增加并未伴随着FcγRI介导的氧化酶活性途径的完成。然而，PMA和FcγRI激动剂检测到的诱导时间进程是一致的，这表明氧化能力的发展可能是由于PMA和表面受体介导的途径所需成分的诱导。已知有几种氧化酶成分可被IFNγ诱导，如氧化酶黄素蛋白、一种b558细胞色素肽以及氧化酶所需的胞质成分，并且这些成分中的一种或一组可能是IFNγ诱导的氧化酶活性的限制因素。
