Christian-Ritter K K, Hill L D, Hoie E B, Zach T L
Department of Pediatrics, Creighton University, Omaha, Nebraska.
Am J Pathol. 1994 Jan;144(1):171-6.
Complement activation in the lung is important in a variety of physiological and pathological conditions. The third component of complement, C3, is the pivotal constituent of the complement cascade. C3 is produced in the lung by several cell types including pulmonary epithelial cells. Because pulmonary epithelial cells and T lymphocytes may interact within the lung to regulate local immune responses, we examined the effect of a T lymphocyte-derived cytokine, interleukin-4 (IL-4) on C3 production by A549 human pulmonary epithelial cells. Treatment of A549 cells with IL-4 increased C3 production in a time- and dose-dependent fashion. Concentrations of IL-4 > or = 0.1 ng/ml significantly increased C3 production. Maximal increase in C3 synthesis occurred after stimulation of A549 cells with IL-4 (10 ng/ml) for 3 days. Preincubation of IL-4 with a neutralizing anti-human IL-4 antibody inhibited IL-4's effect on C3 production. The relative abundance of C3 messenger RNA levels in A549 cells increased following IL-4 treatment, indicating that IL-4's effects on C3 production were pretranslational. Intercellular communication between T lymphocytes and pulmonary epithelial cells via cytokines such as IL-4 may be important in the local regulation of C3 gene expression during the inflammatory response.
补体在肺中的激活在多种生理和病理状况下都很重要。补体的第三成分C3是补体级联反应的关键组成部分。肺中的几种细胞类型包括肺上皮细胞都能产生C3。由于肺上皮细胞和T淋巴细胞可能在肺内相互作用以调节局部免疫反应，我们研究了一种T淋巴细胞衍生的细胞因子——白细胞介素-4（IL-4）对A549人肺上皮细胞产生C3的影响。用IL-4处理A549细胞可使其C3产生呈时间和剂量依赖性增加。IL-4浓度≥0.1 ng/ml时可显著增加C3产生。用IL-4（10 ng/ml）刺激A549细胞3天后，C3合成增加到最大值。将IL-4与中和性抗人IL-4抗体预孵育可抑制IL-4对C3产生的作用。IL-4处理后，A549细胞中C3信使RNA水平的相对丰度增加，表明IL-4对C3产生的作用发生在翻译前。T淋巴细胞和肺上皮细胞之间通过IL-4等细胞因子进行的细胞间通讯在炎症反应期间C3基因表达的局部调节中可能很重要。
