Fw: [EuroLyme] Scientists discover new immune mechanism

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http://www.forbes.com/lifestyle/health/feeds/hscout/2005/09/20/hscout528009.htmlScientist Discover New Immune Mechanism -- Preidt TUESDAY, Sept. 20 (HealthDay News) -- Immune cells use an extensive system of tiny tunnels to deliver signals to distant cells, scientists report.The discovery of this previously unknown cellular communication mechanism may explain why the immune system can respond so quickly to threats, and proves that cells other than neurons can communicate over long distances.Researchers at the University of Pittsburgh School of Medicine found that blood-derived dendritic cells and macrophages -- both antigen-presenting immune system cells -- make use of these tunneling "nanotubes" to relay molecular messages. Using these tiny tunnels, the cells send waves of calcium and other small molecules to cells hundreds of micrometers away.The nanotubes are just 35 and 200 nanometers wide -- 5,000 times smaller than the width of a human hair. At any given time, cells may have up to 75 of these nanotube extensions, of varying lengths."Considering their scale, these nanotubes are allowing communication between fairly distant cells. If instead of a culture dish we were talking about a large metropolitan area, the distance would be about the equivalent of four or five city blocks. That's nothing short of amazing," study co-author D. Salter, an associate professor of immunobiology, said in a prepared statement."Further study may help us better understand how they're involved in the local inflammatory response of the immune system. For instance, we may find that dendritic cells use this network to distribute antigens to other cells and it may be conceivable to follow the entire pathway by tracing the network of tunneling nanotubes," Salter said.The findings appear in the September issue of Immunity.More informationThe U.S. National Library of Medicine has more about immune response.