Dendritic cells are ubiquitous throughout the body, their primary function is as 'danger' detectors, the cells take up antigens from exogenous agents, process and present the antigen on the surface of the cell. Once exposed to antigen the cells mature, and migrate through the lymphatic drainage system to the lymph node where they present the antigen to effector cells of the immune system (such as cytotoxic T lymphocytes). Recently we showed that rather than acting in isolation, the DCs are actually physically interconnected through a network of extremely small tubules which allows clonal activation of populations of cells rather than each cell acting independently. Essentially electrical connectivity between cells allows a single cell to activate several neighbors (over a distance of several hundred microns). These activated cells then migrate toward the signaling cell and take up and process antigen also. Once activated the cells loose their dendritic appearance prior to migrating through the lymphatics. Once at the lymph node they reassume their dendritic morphology. Our studies depend critically on an array of live cell imaging methods; ratiometric measures of calcium concentration, high resolution DIC, Live cell Confocal, Confocal, 2P methods These efforts are now being expanded to include the functional role of nantotubes in immune cross presentation.