Inproceedings: an article in a conference proceedings.
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Exo-vesicles from human activated dendritic cells are released as a function of danger signals and fuse with resting dendritic cells allowing them to present allo-antigens : WA23-136
Title of the conference
1st Joint Meeting of European National Societies of Immunology, under the auspices of EFIS, 16th European Congress of Immunology (ECI)
Paris, France, September 6-9, 2006
Dendritic cells (DCs) realize a surveillance network in ti ssues. Due to their location they are influenced by the environment and as wel l they have an important ability to signal danger to cells from the adaptive immune system. It has been shown that they could release microvesi cles, also called exosomes that might spread processed antigens, however quantitative measure ments as well as functional studies are unclear. Thus we have investigated the microvesicles released from LPS stimulated DCs, regarding their capacity to fuse with the plasma membrane in co -cultures with resting DCs and the transfer of alloantigens. DCs labeled with a flu orescent lipophilic tracer and trapped in collagen matrix were visualized with laser scanning microscopy. Using a surpass algorithm we were able to identify and quantify per cell, secreted microvesicles after LPS stimulation. These secreted microvesicles a re shown not being from endocytic origin, like exosomes, but microvesicles budding from DCs plasma membrane, that we called exo-vesicles, 90% of them having a diameter between 0.2 μm to 0.4μm and they are released as a function of the danger signal such as LPS. We then examined the interaction of these released plasmic membrane-vesicles with DCs labeled with a second lipophilic tracer at dist ance not yet activated by danger signals. With this double vital stainin g we have been able to find that i solated exo-vesicles from activated DCs can fuse with the membrane of resting DCs raising its capacity to present allo -antigens to lymphocytes. We concluded th at DCs are able to respond to danger signals by the release of exo-vesciles. They can fuse with resting DCs i n a distance amplifying after few hours the immunological response by DCs network.
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