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首页> 外文期刊>Journal of cell biology >Class II MHC molecules are present in macrophage lysosomes and phagolysosomes that function in the phagocytic processing of Listeria monocytogenes for presentation to T cells.
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Class II MHC molecules are present in macrophage lysosomes and phagolysosomes that function in the phagocytic processing of Listeria monocytogenes for presentation to T cells.

机译：II类MHC分子存在于巨噬细胞溶酶体和吞噬体中，它们在单核细胞增多性李斯特菌的吞噬过程中发挥功能，呈递给T细胞。

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Phagocytic processing of heat-killed Listeria monocytogenes by peritoneal macrophages resulted in degradation of these bacteria in phagolysosomal compartments and processing of bacterial antigens for presentation to T cells by class II MHC molecules. Within 20 min of uptake by macrophages, Listeria peptide antigens were expressed on surface class II MHC molecules, capable of stimulating Listeria-specific T cells. Within this period, degradation of labeled bacteria to acid-soluble low molecular weight catabolites also commenced. Immunoelectron microscopy was used to evaluate the compartments involved in this processing. Upon uptake of the bacteria, phagosomes containing Listeria fused rapidly with both lysosomes and endosomes. Class II MHC molecules were present in a tubulo-vesicular lysosome compartment, which appeared to fuse with phagosomes, as well as in the resulting phagolysosomes containing internalized Listeria; these compartments were all positive for Lamp 1 and cathepsin D and lacked 46-kD mannose-6-phosphate receptors. In addition, class II MHC and Lamp 1 were co-localized in vesicles of the trans Golgi reticulum, where they were segregated from 46-kD mannose-6-phosphate receptors. Vesicles containing both Listeria-derived components and class II MHC molecules were also observed; some of these may represent vesicles recycling from phagolysosomes, potentially bearing processed immunogenic peptides complexed with class II MHC. These results support a central role for lysosomes and phagolysosomes in the processing of bacterial antigens for presentation to T cells. Tubulo-vesicular lysosomes appear to represent an important convergence of endocytic, phagocytic and biosynthetic pathways, where antigens may be processed to allow binding to class II MHC molecules and recycling to the cell surface.
机译：腹膜巨噬细胞对热杀死的单核细胞增生性李斯特菌的吞噬作用导致吞噬溶酶体区隔中这些细菌的降解，并导致细菌抗原加工成II类MHC分子呈递给T细胞。在巨噬细胞摄取的20分钟内，李斯特菌肽抗原在能够刺激李斯特菌特异性T细胞的II类MHC表面分子上表达。在此期间，标记细菌也开始降解为酸溶性低分子量分解代谢物。免疫电子显微镜用于评估该过程涉及的隔室。吸收细菌后，含有李斯特菌的吞噬体与溶酶体和内体快速融合。 II类MHC分子存在于肾小管水泡溶酶体腔室中，该腔室似乎与吞噬体融合，并且在包含内在性李斯特菌的吞噬体中也存在。这些区室对于Lamp 1和组织蛋白酶D均为阳性，并且缺乏46-kD甘露糖-6-磷酸受体。另外，II类MHC和Lamp 1共定位在反式高尔基网织的囊泡中，在那里它们与46-kD甘露糖-6-磷酸受体分离。还观察到既包含李斯特菌来源的成分又包含II类MHC分子的囊泡;其中一些可能代表从吞噬体中回收的囊泡，吞噬体可能带有与II类MHC复合的经过加工的免疫原性肽。这些结果支持了溶酶体和吞噬溶酶体在细菌抗原加工中的重要作用，以呈递给T细胞。肾小管囊泡溶酶体似乎代表着内吞，吞噬和生物合成途径的重要融合，其中可以加工抗原以使其结合II类MHC分子并再循环至细胞表面。

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