[Human monocytes show chemotaxis in response to cholesteatoma debris].

Using a microchamber technique, we tested cholesteatoma debris and certain of its constituents for effects on the migration of human peripheral blood monocytes and polymorphonuclear leukocytes. Cholesteatoma debris induced significant migration of monocytes. When the individual constituents of cholesteatoma debris, i.e., alpha-keratin, cholesterol, lauric acid and lipopolysaccharides, were tested for monocyte chemotaxis, only alpha-keratin induced significant monocyte migration. alpha-keratin extracted from the cholesteatoma debris with 8 M urea also induced migration of monocytes with a bell-shaped dose-response curve, which is frequently encountered with chemoattractants. Therefore, cholesteatoma debris and one of its components, alpha-keratin, are potent chemoattractants for human monocytes. On the other hand, cholesteatoma debris showed no significant chemotactic effect on polymorphonuclear leukocytes. Based on the present and our previous results, cholesteatoma debris acts on monocytes/macrophages as a strong chemotactant, a potent activating (priming) factor, and an inducer of production of tumor necrosis factor, which is a bone-resorbing cytokine. Therefore, we concluded that macrophages induced by cholesteatoma debris may play an important role in the pathogenesis of bone resorption in cholesteatoma otitis.