Localization of interleukin-1 in human cholesteatoma

Recent studies by other investigators have shown that interleukin-1 (IL-1) promotes bone resorption by stimulating various cells. Interleukin-1 not only stimulates collagenase production by fibroblasts and macrophages, but also acts as an osteoclast-activating factor. In this study, IL-1 was localized in human cholesteatoma tissues using both immunoperoxidase and immunofluorescent-staining methods with specific monoclonal antibodies. Highly concentrated IL-1 was found in the epithelial layer and granulation tissue. More specifically, intense staining was seen in basal and spinous cells of the epithelial layer, and in fibroblasts and macrophages of the granulation layer. We also located IL-1 in the normal external ear canal skin; however, the intensity of the staining in the cholesteatoma epithelium was found to be stronger. The presence of IL-1 in the epithelial layer and granulation tissue of the cholesteatoma suggests that IL-1 from the stimulated keratinocytes of the cholesteatoma could be one factor responsible for the markedly increased bone resorption observed in cholesteatoma patients.