Colony-stimulating factor in middle ear cholesteatoma.

Granulocyte-macrophage colony stimulating factor (GM-CSF) was found in human middle ear cholesteatoma tissues by immunohistochemical technique using mouse monoclonal anti-(human) GM-CSF IgG. Immunofluorescent staining showed the presence of GM-CSF in the peribasal area, in some suprabasal cells of the epithelium, and in the inflammatory connective tissue, especially in the monocytes and fibroblasts. These findings were confirmed by the immunoperoxidase method. Staining of the external ear canal epithelium, however, was significantly weaker than that of the cholesteatoma epithelium. The presence of GM-CSF in cholesteatoma appears to be a response to inflammation occurring in the middle ear cavity. Moreover, our in vitro study showed that GM-CSF induced the proliferation and protein synthesis of basal keratinocytes. This study suggests that GM-CSF is involved in the development and destructive effects of middle ear cholesteatoma.