Immune system cells are connected to each other by an extensive network of tiny tunnels that, like a building's hidden pneumatic tube system, are used to shoot signals to distant cells. This surprising discovery, being reported by two University of Pittsburgh School of Medicine researchers in the September issue of the journal Immunity, may explain how an immune response can be so exquisitely swift. The research not only proves cells other than neurons are capable of long-distance communication, but it reveals a hereto-unknown mechanism cells use for exchanging information.
Blood-derived dendritic cells and macrophages, both antigen-presenting cells, make use of these so-called tunneling nanotubules to relay molecular messages, report Simon C. Watkins, Ph.D., and Russell D. Salter, Ph.D. Further research may show there are additional cell types with these microscopic tunnel connections. Thus far, their studies suggest the tunnels do not exist between commonly used fibroblast and tumor cell lines.
Interestingly, if not for a minor mishap while carrying out an experiment, the authors might not have discovered the existence of these physical structures and conducted the studies that revealed their role in intercellular communication.
Using a custom-built, multi-camera live cell microscopic imaging system, they report that, in a matter of seconds, dendritic cells and macrophages can send waves of calcium and other small molecules to cells hundreds of micrometers away. Each nanotubule measures between 35 and 200 nanometers across - 5000 times smaller than the width of a human hair - and at any given time, cells may have up to 75 of these extensions, each of varying lengths.
"Considering their scale, these nanotubules are allowing communication between fairly distant cells. If instead of a culture dish we were talking about a large metropolitan are
Source:University of Pittsburgh Medical Center