肠毒素C2第20和22位氨基酸对其超抗原活性的影响  

Effect of 20 and 22 amino acid on superantigen activity of staphylococcal enterotoxin C2

作　　者：刘彦礼[1] 牛荣成[1] 徐明恺[2] 李旭[2] 苏振成[2] 张惠文[2] 

机构地区：[1]新乡医学院生命科学技术学院,新乡453003 [2]中国科学院沈阳应用生态研究所,沈阳110016

出　　处：《中国免疫学杂志》2014年第12期1596-1600,共5页Chinese Journal of Immunology

基　　金：国家科技重大专项重大新药创制(No.2012ZX09102301013);新乡医学院博士科研启动基金(No.505033)资助项目

摘　　要：目的:揭示突变蛋白SEC2(T20L/G22E)超抗原活性较野生型SEC2显著增强的潜在机制。方法:WST-1法检测突变蛋白SEC2(T20L/G22E)在体外刺激小鼠脾淋巴细胞增殖活性,进一步应用流式细胞术和荧光定量PCR技术分别检测CD4+和CD8+T淋巴细胞增殖、特异性VβT淋巴细胞增殖以及相关细胞因子mRNA丰度变化。结果:与野生型SEC2相比,突变蛋白SEC2(T20L/G22E)能够在体外显著刺激小鼠脾淋巴细胞增殖,但二者具有相似的特异性VβT淋巴细胞增殖谱,并且SEC2(T20L/G22E)能够较rSEC2激活更多携带有Vβ5.3、Vβ8.1及Vβ8.3的T淋巴细胞;进一步体内实验发现SEC2(T20L/G22E)能够较rSEC2激活更多外周血和脾脏中CD4+和CD8+T淋巴细胞增殖及相关细胞因子的表达。结论:突变蛋白SEC2(T20L/G22E)超抗原活性增强的机制可能是用亮氨酸和谷氨酸替代原来20和22位上的氨基酸后提高了SEC2(T20L/G22E)与特异性TCR-Vβ的亲和力,进一步激活更多的SEC2特异性T淋巴细胞,最终引起T淋巴细胞亚型的显著性增殖,同时诱导更多与抗肿瘤、增殖相关的细胞因子的表达。Objective：To investigate the improved superantigen activity of SEC2（T20L/G22E） compared with recombinant staphylococcal enterotoxins C 2 （ rSEC2 ）.Methods： The proliferation of spleen lymphocytes and T-cell subpopulations induced by rSEC2 and SEC2（T20L/G22E） were examined by WST-1 and flow cytometry separately,and the gene expression of cytokines and Vβspecificities were quantified by real-time PCR.Results： WST-1 and Flow cytometry assays showed that the superantigen activity of SEC2（T20L/G22E） was improved due to enhanced T-cell stimulating potency,resulting in massive activation of T-cells,particularly CD4＋and CD8＋T-cells.Quantitative real-time PCR assay showed that despite similar Vβspecificities induced by rSEC 2 and SEC2 （T20L/G22E）,the quantities of activated T-cells bearing specific Vβwere different,and SEC2（T20L/G22E） could stimulate more gene expression of associated cytokines simultaneously.Conclusion： The results strongly suggested that the increased SEC 2 （ T20L/G22 E）-TCR-binding affinity contributed to more T-cells activation and cytokine release ,which elicit powerful immune activition.

关 键 词：金黄色葡萄球菌肠毒素C2 超抗原 T淋巴细胞 细胞因子 

分 类 号：Q819[生物学—生物工程]