Human B Cell-Derived Lymphoblastoid Cell Lines Constitutively Produce Fas Ligand and Secrete MHCII(+)FasL(+) Killer Exosomes.
Human B Cell-Derived Lymphoblastoid Cell Lines Constitutively Produce Fas Ligand and Secrete MHCII(+)FasL(+) Killer Exosomes.
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DOI：
10.3389/fimmu.2014.00144
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发表时间：
2014
影响因子：
7.3
通讯作者：
Lundy SK
中科院分区：
文献类型：
--
作者：
Klinker MW;Lizzio V;Reed TJ;Fox DA;Lundy SK
外泌体介导的免疫抑制是一个新兴的概念，在各种炎症背景下，包括同种异体移植的免疫治疗中具有潜在的巨大效用。含有凋亡诱导分子Fas配体（FasL）的外泌体已经证明在动物模型中过继转移后抑制抗原特异性免疫应答的功效。我们在此报道了一种非常高频率的人B细胞衍生的淋巴母细胞样细胞系（LCL）组成型产生MHCII+FasL+外泌体，其可以诱导CD 4 + T细胞的凋亡。本研究测试的所有LCL（>20个独立的细胞系）均显示出FasL的稳健表达，但在细胞表面上没有可检测到的FasL。鉴于这种细胞内隔离，我们假设LCL中的FasL保留在分泌溶酶体中并通过外泌体分泌。事实上，我们发现MHCII和FasL蛋白都存在于LCL衍生的外泌体中，并且使用基于珠粒的外泌体捕获测定证明了MHCII+FasL+外泌体在由LCL分泌的那些外泌体中的存在。使用两种独立的实验方法，我们证明了LCL衍生的外泌体能够在自体CD4+ T细胞中诱导抗原特异性凋亡。这些结果表明，LCL衍生的外泌体可能是免疫抑制性外泌体的现实来源，其可以减少或消除移植受体中针对供体衍生抗原的T细胞介导的应答。
Immune suppression mediated by exosomes is an emerging concept with potentially immense utility for immunotherapy in a variety of inflammatory contexts, including allogeneic transplantation. Exosomes containing the apoptosis-inducing molecule Fas ligand (FasL) have demonstrated efficacy in inhibiting antigen-specific immune responses upon adoptive transfer in animal models. We report here that a very high frequency of human B cell-derived lymphoblastoid cell lines (LCL) constitutively produce MHCII+FasL+ exosomes that can induce apoptosis in CD4+ T cells. All LCL tested for this study (>20 independent cell lines) showed robust expression of FasL, but had no detectable FasL on the cell surface. Given this intracellular sequestration, we hypothesized that FasL in LCL was retained in the secretory lysosome and secreted via exosomes. Indeed, we found both MHCII and FasL proteins present in LCL-derived exosomes, and using a bead-based exosome capture assay demonstrated the presence of MHCII+FasL+ exosomes among those secreted by LCL. Using two independent experimental approaches, we demonstrated that LCL-derived exosomes were capable of inducing antigen-specific apoptosis in autologous CD4+ T cells. These results suggest that LCL-derived exosomes may present a realistic source of immunosuppressive exosomes that could reduce or eliminate T cell-mediated responses against donor-derived antigens in transplant recipients.