Direct visualization of peptide/MHC complexes at the surface and in the intracellular compartments of cells infected in vivo by Leishmania major.
Direct visualization of peptide/MHC complexes at the surface and in the intracellular compartments of cells infected in vivo by Leishmania major.
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DOI：
10.1371/journal.ppat.1001154
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发表时间：
2010-10-14
期刊：
影响因子：
6.7
通讯作者：
Mougneau E
中科院分区：
文献类型：
--
作者：
Muraille E;Gounon P;Cazareth J;Hoebeke J;Lippuner C;Davalos-Misslitz A;Aebischer T;Muller S;Glaichenhaus N;Mougneau E
原生动物和细菌感染各种类型的吞噬细胞，包括巨噬细胞、单核细胞、树突细胞和嗜酸性粒细胞。然而，尚不清楚这些细胞中的哪一个在体内加工和呈递微生物抗原，以及寄生虫肽在哪个细胞区室中加载到主要组织相容性复合物分子上。为了解决这些问题，我们感染易感BALB/c（H-2d）小鼠与重组利什曼原虫主要寄生虫表达荧光示踪剂。为了直接可视化将寄生虫衍生肽呈递给CD 4 + T细胞的抗原呈递细胞，我们已经产生了与结合至I-Ad主要组织相容性复合物II类分子的寄生虫LACK抗原衍生的抗原肽反应的单克隆抗体。免疫金电镜分析表明，在体内感染的细胞内的I-Ad/LACK复合物存在于树突状细胞，嗜酸性粒细胞和巨噬细胞/单核细胞的无鞭毛体的吞噬体的膜。在树突状细胞和巨噬细胞中，这些复合物也存在于不含无鞭毛体的较小囊泡中。I-Ad/LACK复合物在树突状细胞表面的存在下，但既不是在巨噬细胞的质膜上，也不是在嗜酸性粒细胞上，通过流式细胞术和通过用高度敏感的LACK特异性杂交瘤孵育分选的吞噬细胞来独立地证实。总之，我们的研究结果表明，来自利什曼原虫蛋白的肽装载到感染的吞噬细胞的吞噬体中的主要组织相容性复合物II类分子上。尽管这些复合物在树突状细胞中被转运到细胞表面，因此允许刺激寄生虫特异性CD 4 + T细胞，但这不会发生在其他吞噬细胞中。据我们所知，这是第一项研究，其中主要组织相容性复合物II类分子结合的肽来源于寄生虫蛋白质已被可视化内和表面的细胞被感染的体内。吞噬作用是一种细胞过程，它允许细胞膜吞噬固体颗粒，如细菌或寄生虫，并导致形成胞质内囊泡，即吞噬体。能够进行吞噬作用的细胞类型称为吞噬细胞，包括单核细胞、巨噬细胞、树突细胞和嗜酸性粒细胞。所有这些细胞表达主要组织相容性复合物II类分子，尽管水平不同。这些分子允许将病原体衍生的肽呈递给CD 4 + T淋巴细胞，这是一种提醒免疫系统发生感染危险的机制。为了使病原体衍生肽和主要组织相容性复合物II类分子之间形成复合物的细胞内隔室可视化，我们已经产生了一种单克隆抗体，该抗体与细胞内寄生虫主要利什曼原虫的免疫显性抗原衍生的肽反应，该抗原与鼠主要组织相容性复合物II类分子结合。我们已经表明，这些复合物存在于各种类型的吞噬细胞的吞噬体上，但只有树突状细胞将这些复合物输出到质膜，从而激活病原体特异性T细胞。
Protozoa and bacteria infect various types of phagocytic cells including macrophages, monocytes, dendritic cells and eosinophils. However, it is not clear which of these cells process and present microbial antigens in vivo and in which cellular compartments parasite peptides are loaded onto Major Histocompatibility Complex molecules. To address these issues, we have infected susceptible BALB/c (H-2d) mice with a recombinant Leishmania major parasite expressing a fluorescent tracer. To directly visualize the antigen presenting cells that present parasite-derived peptides to CD4+ T cells, we have generated a monoclonal antibody that reacts to an antigenic peptide derived from the parasite LACK antigen bound to I-Ad Major Histocompatibility Complex class II molecule. Immunogold electron microscopic analysis of in vivo infected cells showed that intracellular I-Ad/LACK complexes were present in the membrane of amastigote-containing phagosomes in dendritic cells, eosinophils and macrophages/monocytes. In both dendritic cells and macrophages, these complexes were also present in smaller vesicles that did not contain amastigote. The presence of I-Ad/LACK complexes at the surface of dendritic cells, but neither on the plasma membrane of macrophages nor eosinophils was independently confirmed by flow cytometry and by incubating sorted phagocytes with highly sensitive LACK-specific hybridomas. Altogether, our results suggest that peptides derived from Leishmania proteins are loaded onto Major Histocompatibility Complex class II molecules in the phagosomes of infected phagocytes. Although these complexes are transported to the cell surface in dendritic cells, therefore allowing the stimulation of parasite-specific CD4+ T cells, this does not occur in other phagocytic cells. To our knowledge, this is the first study in which Major Histocompatibility Complex class II molecules bound to peptides derived from a parasite protein have been visualized within and at the surface of cells that were infected in vivo. Phagocytosis is a cellular process that allows the engulfment of solid particles such as bacteria or parasites by the cell membrane and leads to the formation of an intracytoplasmic vesicle, the phagosome. Cell types that are capable of phagocytosis are called phagocytes and include monocytes, macrophages, dendritic cells and eosinophils. All these cells express Major Histocompatibility Complex class II molecules, although at different levels. These molecules allow the presentation of pathogen-derived peptides to CD4+ T lymphocytes, a mechanism that alerts the immune system of the occurrence of an infectious danger. In order to visualize the intracellular compartments in which complexes between pathogen-derived peptides and Major Histocompatibility Complex class II molecules are formed, we have generated a monoclonal antibody that reacts to a peptide derived from an immunodominant antigen of the intracellular parasite Leishmania major bound to a murine Major Histocompatibility Complex class II molecule. We have shown that these complexes are present on the phagosomes from various types of phagocytes but that only dendritic cells export these complexes to the plasma membrane, allowing the activation of pathogen-specific T cells.
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影响因子：
64.8
作者：
Houde, M;Bertholet, S;Desjardins, M
通讯作者：
Desjardins, M
DOI：
10.1073/pnas.89.19.9000
发表时间：
1992-10-01
影响因子：
11.1
作者：
IWABUCHI, K;NAKAYAMA, K;LOH, DY
通讯作者：
LOH, DY
影响因子：
32.4
作者：
Lazarski, CA;Chaves, FA;Sant, AJ
通讯作者：
Sant, AJ
影响因子：
6.7
作者：
De Trez C;Magez S;Akira S;Ryffel B;Carlier Y;Muraille E
通讯作者：
Muraille E
影响因子：
32.4
作者：
Dadaglio, G;Nelson, CA;Unanue, ER
通讯作者：
Unanue, ER