[Capillary endothelial cells in sarcoidosis--electron microscopic findings]

The distribution of von Willebrand (vW) factor, thrombomodulin (TM) and fibronectin (FN) in the capillary endothelial cells of the lung of patients with sarcoidosis was investigated using their monoclonal or polyclonal antibodies. The vW factor showed strong reaction with exudation towards outside and irregular dilatation or occlusion in the capillary walls surrounded sarcoid granulomas and capillaries in the remote area. The area showing alveolitis disclosed also strong reaction with exudation by vW factor. TM having a anti-coagulating function showed a very low reactivity in the lung tissues with or without of granulomas in sarcoidosis at light microscopic level, but in electron microscopically, strong reaction and broad distribution in capillary endothelial cells, involving luminal occlusion and reaction in subendothelial region. FN showed new and many capillaries formation in the growing collagenous tissues between the old sarcoid granulomas suggesting neocapillarization originating from endothelial cells. These findings suggest that the capillary endothelial cells participate strongly in formal genesis of sarcoid granulomas.