树突状细胞外泌体免疫作用机制的初步研究

为了研究外泌体（exosome）作为肿瘤疫苗刺激免疫应答作用的机制，从正常人外周血单个核细胞诱导树突状细胞（DC）制备负载肿瘤抗原的DC外泌体（Dex），研究其在DC有无或DC成熟状态不同的情况下刺激T细胞增殖的能力；通过实验阻断DC外泌体上一些分子（CD11a、CD11b、CD11c、CD54、MFG-E8及CD83）后检测外泌体免疫学功能的改变；采用共聚焦显微镜检测DC对外泌体的吞噬作用，用流式细胞仪检测阻断外泌体表面分子对DC吞噬外泌体作用的影响。结果表明：在无DC存在或未成熟DC存在的情况下未成熟DC外泌体（imDex）和成熟DC外泌体（mDex）均不能有效地激活T细胞；不同的促成熟因子（LPS、TNF-α、CpG、CD40L）诱导成熟的DC所分泌的外泌体在数量上无明显差别，但在功能上有显著差异；Dex表面分子CD11a、CD11b、CD11c、CD54、MFG-E8及CD83与其功能有关，阻断这些分子均能不同程度地抑制Dex对T细胞刺激的作用；共聚焦显微镜和流式细胞仪检测表明阻断CD11a、cD54抑制了Dex靶向DC及被DC吞噬。结论：外泌体可以通过其表面分子靶向DC进而引起T细胞免疫应答。

Immunity Mechanism of Exosomes Derived from Dendritic Cells

To confirm the mechanism of exosomes as tumor vaccines inducing immunity response, dendritic cells (DCs) were induced from human peripheral blood mononuclear cells, while exosomes were isolated from DC loaded tumor antigen. The effect of exosomes on priming T cell proliferation was analysed under conditions with or without DCs, or DCs at different mature stages. The function of exosomes in immunity was detected through block test after blocking some molecules (CD11a, CD11b, CD11c, CD54, MFG-E8 and CD83). The effect of DCs on embedded exosomes was observed by confocal microscopy, the effect of blocking surface molecules on exosomes on DC-embedding exosomes was assayed by flow cytometry. The results indicated that both exosomes derived from imDC (imDex) and exosomes derived from mDC (mDex) could not prime T cells without DC or with imDC. The exosomes derived from mDC induced with different cytokines (LPS, TNF-alpha, CpG, CD40L) were no significant difference in concentrations but were different in effect. The immunity function of exosomes depended on CD11a, CD11b, CD11c, CD54, MFG-E8 and CD83 molecules, the effect of priming T cells is reduced when these molecules were blocked. Confocal microscopy and FACS assay showed that blocking CD11a and CD54 could inhibit exosome-targeted DC and DC-embedded exosomes. It is concluded that the exosomes target DCs through their surface molecules, therefore results in immune response of T cells.