Localization of fibronectin in human middle ear cholesteatoma

Fibronectin was localized in human cholesteatoma tissues by immunohistochemical methods. The avidin-biotin-peroxidase complex staining method was used with specific fibronectin antibody. Fibronectin appeared to be localized in the matrix of the cholesteatoma studied, particularly on the surface of the cell membranes and the nuclei of the basal cells and in connective tissue. Fibronectin was not seen in the granular layer or in the keratin area. Fibronectin was found on the surface of granulation tissue, mononuclear cells, fibroblasts and endothelial cells of blood vessels. These findings were confirmed by the immunofluorescent staining method. Our previous study showed that fibronectin induced a migration of keratinocytes, macrophages and fibroblasts demonstrated by the Boyden's chamber chemotaxis assay. Macrophages and fibroblasts were shown to produce collagenase, a bone resorption factor, in cholesteatomatous tissue. The present study showed the presence of fibronectin in the matrix of cholesteatoma and granulation tissue, suggesting that fibronectin might play an important role in the clinical development and invasive behavior of cholesteatoma.