Mechanisms of antigen-specific DNA vaccines for allergies

APC启动T细胞介导的针对外源Ag的免疫应答。树突状细胞是专职的APC，其发挥独特的作用，包括Ag非特异性捕获、初始T细胞的引发和Th 1诱导，而B细胞通常缺乏这些功能。在这项研究中，我们发现了新的方面，小鼠B细胞作为APC使用CpG寡脱氧核苷酸（CpG）与Ag缀合。B细胞作为有效的APC独立于表面Ig。这一特性被CpG介导的Ag摄取和呈递所取代，其仅在CpG共价结合到Ag时才起作用。用CpG偶联的Ag培养的B细胞不仅增强Th 1细胞产生IFN-γ，而且诱导未致敏的T细胞向Th 1分化。这些性质与B细胞上CD 40、CD 86和II类分子表达的增加以及细胞协同产生IL-12平行。据我们所知，这是第一个报告，揭示B细胞与树突状细胞共同的内在特性，如Ag-非特异性捕获和呈递，以及诱导Th 1分化的未致敏的T细胞。

APCs initiate T cell-mediated immune responses against foreign Ags. Dendritic cells are professional APCs that play unique roles, including Ag-nonspecific capture, priming of naive T cells and Th1 induction, whereas B cells generally lack these functions. In this study, we uncovered novel aspects of murine B cells as APCs using CpG oligodeoxynucleotides (CpG) conjugated with an Ag. B cells served as efficient APCs independently of surface Igs. This characteristic was underlay by the CpG-mediated Ag uptake and presentation, which was functional only when CpG were covalently conjugated to Ag. The B cells cultured with CpG-conjugated Ag not only enhanced the IFN-γ formation by Th1 cells but also induced Th1 differentiation from unprimed T cells. These natures were in parallel with the increase in the expression of CD40, CD86, and class II molecules on B cells, and the coordinated production of IL-12 by the cells. To our knowledge, this is the first report revealing that B cells share with dendritic cells common intrinsic characteristics, such as the Ag-nonspecific capture and presentation, and the induction of Th1 differentiation from unprimed T cells.