Are there functional gap junctions or junctional hemichannels in macrophages?
The existence of functional gap junctions in migratory cells of the immune system is a controversial issue. In this report, we have focused on one particular cell type, namely the macrophages, because connexin- 43, a protein that forms gap junctions, has been described in peritoneal macrophages and a macrophage cell line (J774), by Northern and Western blot analysis. To test whether these cell types expressed functional gap junctions, we assayed dye coupling by intracellular injection of Lucifer Yellow. We observed that nonstimulated macrophages are not coupled among themselves and did not form functional gap junctions with an epithelial cell line, which expresses functional gap junctions formed by connexin-43. Dye coupling was also not detected between macrophages previously activated by lipopolysaccharide or interferon-gamma. We further examined the presence of functional coupling using the more sensitive technique of dual whole cell patch- clamp, and again, did not find electrical c
