Lack of detection of factor VIII in sarcoidal epithelioid cells

We investigated the possibility that epithelioid cells in sarcoidosis contain abundant angiotensin-converting enzyme, because these cells are derived from endothelial cells, which normally contain the enzyme in abundance. Granulomas from 9 patients with sarcoidosis were examined for the presence of the endothelial cell marker, factor VIII, by immunofluorescence microscopy using monospecific anti-human factor VIII antibody. Strong factor VIII-specific fluorescence was detected in the endothelial cells but no fluorescence was observed in the epithelioid cells. These results do not support the origin of epithelioid cells in sarcoidosis from endothelial cells as an explanation for their abundance of angiotensin-converting enzyme.