| 摘要: |
| 目的:研究IL-18是否参与调节T细胞通过直接接触激活的单核细胞的功能及其细胞内机制。方法:采用磁珠分离技术从健康人外周血分离纯化T细胞和单核细胞,被植物血凝素(PHA)预刺激的T细胞用多聚甲醛固定后按41与单核细胞共培养。采用ELISA法测定上清中肿瘤坏死因子(TNF)-α和IL-18的含量。采用流式细胞仪分析单核细胞表面IL-18受体α链的表达(IL-18Rα)。结果:PHA刺激48 h或72 h的T细胞诱导单核细胞产生的TNF-α显著高于未接受PHA刺激的T细胞。单独培养的单核细胞和T细胞几乎不产生TNF-α。T细胞直接接触可诱导单核细胞产生IL-18,且该作用能被核因子(NF)-κB抑制剂N-乙酰基-L-半胱氨酸(NAC)和磷脂酰肌醇(PI)3-激酶抑制剂LY294002分别抑制,但有丝分裂原激活蛋白激酶(MAPK)抑制剂SB203580对之无作用。与T细胞共孵育24 h的单核细胞表面IL-18Rα的表达明显上调。单克隆的IL-18中和抗体呈剂量依赖性抑制与T细胞共孵育的单核细胞产生TNF-α。IL-18不能促进单纯的单核细胞产生TNF-α,但呈剂量依赖性地促进由于接触T细胞膜而激活的单核细胞产生TNF-α,且该作用可被NAC和LY294002分别拮抗,但不受SB203580影响。结论:T细胞可通过直接接触诱导单核细胞产生TNF-α和IL-18,上调单核细胞表面的IL-18R,并激活单核细胞内的NF-κB和PI3-激酶。IL-18可增强T细胞接触激活的单核细胞分泌致炎细胞因子的功能,该作用依赖细胞内NF-κB和PI3-激酶途径的激活。 |
| 关键词: T淋巴细胞 单核细胞 巨噬细胞 细胞接触 白细胞介素18 信号转导 |
| DOI：10.3724/SP.J.1008.2009.0157 |
| 投稿时间：2008-06-17修订日期：2008-09-08 |
| 基金项目:上海市浦江人才计划(06PJ14121). |
|
| Interleukin-18 enhances cytokine secretion by monocytes activated through direct contact with T lymphocytes |
| HUO Hong1△,ZHANG Cong-xin2△,ZHAO Dong-bao3,DAI Sheng-ming3* |
| (1.Department of Nephrology,PLA General Hospital of the Second Artillery,Beijing 100088,China*2.Department of Science Research Administration,Second Military Medical University,Shanghai 200433*3.Department of Rheumatology & Immunology,Changhai Hospital,Second Military Medical University,Shanghai 200433) |
| Abstract: |
| Objective:To study whether interleukin (IL)-18 is involved in the activation of monocytes through direct contact with T cells and the related intracellular mechanism. Methods: T cells and monocytes were isolated and purified from the peripheral blood of healthy donors by magnetic beads. Phytohemagglutinin (PHA) pre-stimulated T cells were fixed by 1% paraformaldehyde and were then co-cultured with monocytes at a T cellmonocyte ratio of 41. TNF-α and IL-18 levels in the supernatants were assayed by ELISA. Expression of IL-18 receptor α chain (IL-18Rα) on the surface of monocytes was analyzed by flow cytometry.Results: Monocytes activated by PHA-stimulated T cells produced significantly more TNF-α than by unstimulated T cells; non-cultured T cells or monocytes hardly produced any TNF-α. Upon direct cellular contact, PHA pre-stimulated T cells also up-regulated IL-18Rα expression on the surface of monocytes and induced IL-18 production in monocytes, which could be suppressed by nuclear factor (NF)-κB inhibitor (N-acetyl-L-cysteine, NAC) or phosphatidyl-inositol (PI) 3 kinase inhibitor (LY294002), but not by mitogen activated protein kinase (MAPK) inhibitor (SB203580). Neutralizing anti-IL-18 monoclonal antibody dose-dependently inhibited the production of TNF-α by monocyte-stimulated T cells. IL-18 failed to induce TNF-α production by cultured monocytes alone, while dose-dependently enhanced TNF-α production in monocyte-stimulated T cells, which could be inhibited by NAC or LY294002, but not by SB203580.Conclusion: By direct cellular contact T cells can stimulate monocytes to produce TNF-α and IL-18, up-regulate IL-18 receptor expression in monocytes, and activate intracellular NF-κB and PI3 kinase pathways. IL-18 can enhance T cell ability to stimulate TNF-α production by monocytes, which is dependent on the activation of NF-κB and PI3 kinase pathways. |
| Key words: T lymphocytes monocytes macrophages cell contact interleukin-18 signal transduction |
