Mody C H, Buser D E, Syme R M, Woods D E
Department of Internal Medicine, University of Calgary, Alberta, Canada.
Infect Immun. 1995 May;63(5):1800-5. doi: 10.1128/iai.63.5.1800-1805.1995.
Pseudomonas aeruginosa is a gram-negative bacterium that is responsible for devastating acute and chronic infections, which include bronchiectasis in cystic fibrosis, nosocomial pneumonia, and infection of burn wounds. Previous studies have demonstrated that these patients have impaired host responses, including cell-mediated immune responses, which are important in anti-Pseudomonas host defense. The P. aeruginosa exoproduct, exoenzyme S, has a number of characteristics which suggest that it might be important in cell-mediated immunity. To determine whether exoenzyme S activates lymphocytes to proliferate, peripheral blood mononuclear cells (PBMC) from normal volunteers were stimulated with purified exoenzyme S, and the lymphocyte response was assessed by measuring [3H]thymidine uptake and by counting the number of cells after various times in culture. Ninety-five percent of healthy adult donors had a lymphocyte response to exoenzyme S. The optimal lymphocyte response occurred on day 7, with 4 x 10(5) PBMC per microtiter well when cells were stimulated with 10 micrograms exoenzyme S per ml. [3H]thymidine uptake correlated with an increase in the number of mononuclear cells, indicating that proliferation occurred. In unseparated PBMC, T cells, and to a lesser extent B cells, proliferated. Purified T cells proliferated, while purified B cells proliferated only after the addition of irradiated T cells. Thus, T lymphocytes are necessary and sufficient for the proliferative response to exoenzyme S. We speculate that exoenzyme S from P. aeruginosa is important in T-lymphocyte-mediated host defense to P. aeruginosa. In strategies to enhance impaired cell-mediated immunity, exoenzyme S should be considered as a potential stimulant.
铜绿假单胞菌是一种革兰氏阴性菌，可引发严重的急性和慢性感染，包括囊性纤维化患者的支气管扩张、医院获得性肺炎以及烧伤创面感染。先前的研究表明，这些患者的宿主反应受损，包括细胞介导的免疫反应，而这种反应在抗铜绿假单胞菌的宿主防御中很重要。铜绿假单胞菌的外毒素产物——外毒素S具有多种特性，这表明它可能在细胞介导的免疫中发挥重要作用。为了确定外毒素S是否能激活淋巴细胞增殖，我们用纯化的外毒素S刺激正常志愿者的外周血单核细胞（PBMC），并通过测量[3H]胸腺嘧啶核苷摄取量以及在培养不同时间后计数细胞数量来评估淋巴细胞反应。95%的健康成年供体对外毒素S有淋巴细胞反应。最佳淋巴细胞反应出现在第7天，当每微升孔中接种4×10(5)个PBMC，并用每毫升10微克外毒素S刺激细胞时。[3H]胸腺嘧啶核苷摄取量与单核细胞数量增加相关，表明发生了增殖。在未分离的PBMC中，T细胞以及程度较轻的B细胞发生了增殖。纯化的T细胞增殖，而纯化的B细胞仅在添加经辐照的T细胞后才增殖。因此，T淋巴细胞对于对外毒素S的增殖反应是必要且充分的。我们推测，铜绿假单胞菌的外毒素S在T淋巴细胞介导的针对铜绿假单胞菌的宿主防御中很重要。在增强受损细胞介导免疫的策略中，外毒素S应被视为一种潜在的刺激剂。
