贝氏柯克斯体重组膜蛋白抗原激活树突状细胞诱导特异性免疫应答

目的分析贝氏柯克斯体(Coxiella burnetii,Cb)膜蛋白抗原对树突状细胞(dendritic cells,DCs)的激活作用,筛选能有效激活DCs的蛋白抗原,探讨该蛋白抗原间接激活T细胞的作用。方法从健康成年人外周血中分离单核细胞,加入GM-CSF和IL-4体外培养单核细胞成未成熟DCs;分别用Cb的5种重组膜蛋白IcmO、EnhA、SecB、Lo1A、HspB刺激DCs;用流式细胞仪(fluorescence activated cell sorter,FACS)检测刺激后DCs表面分子表达。结果 SecB刺激的DCs表达CD83,CD86,CD80,CD54,CD58,和CD40水平显著高于其它4种蛋白;将SecB激活DCs或SecB激活DCs培养上清刺激T淋巴细胞,FACS检测显示刺激后CD4+和CD8+细胞高水平表达的T淋巴细胞活化标志CD69以及细胞因子IFN-γ和TNF-α。结论 SecB膜蛋白抗原能有效激活DCs和它所激活DCs能够诱导特异性细胞免疫应答,为贝氏柯克斯体潜在保护性抗原。

Specific immune response of induced by human dendritic cells activated with membrane proteins of Coxiella burnetii

Dendritic cells（DCs）are potent antigen-presenting cells（APCs）which bridge the innate and adaptive immune responses through direct pathogen neutralization,cytokine production and T cell activation.Coxiella burnetii（C.burnetii）is an obligate intracellular bacterium and the etiological agent of Q fever.In this study,recombinant proteins IcmO,EnhA,SecB,Lo1A,and HspB of C.burnetii were used to stimulate human monocyte-derived DCs.Results showed that SecB-activated DCs exhibited significantly higher expression of CD83,CD86,CD80,CD54,CD58,and CD40 compared with other proteins and having ability to product Th1-promoting interleukin-12 in analysis of fluorescence activated cell sorter（FACS）.After stimulating T cells by SecB-activated DCs or culture supernatant of SecB-activated DCs,both CD4＋ and CD8＋ T cells exhibited highlexpressions of CD69（an activation marker of lymphocytes）and cytokines（IFN-γ and TNF-α）.These results suggest that SecB could efficiently activate DCs and the activated DCs have a capability to induce a specific T cell immune response,which indicate that SecB is a potential protective antigen for C.burnetii.