It is well known that cholesteatoma otitis is characterized by bone destruction, but the mechanisms of this destruction remain to be clarified. Interleukin-1 alpha (IL-1 alpha), tumor necrosis factor-alpha (TNF-alpha) and parathyroid hormone-related protein (PTHrP) were immunohistologically demonstrated in the epithelia of cholesteatoma tissues obtained from patients with cholesteatoma, at ear surgery, in the present study. The staining for IL-1 alpha was marked in epithelial keratinocytes. The existence of PTHrP was demonstrated in the keratinocytes of cholesteatoma epithelium. PTHrP contents in keratinocytes on spinous layers had accumulated to a greater extent than those in basal layers. Compared with the staining of PTHrP in external ear canal epidermis, cholesteatomatous keratinocytes were more strongly stained. Further more, the effects of cholesteatomatous debris on generation of IL-1 alpha and TNF-alpha in cholesteatoma keratinocytes and normal human epidermal keratinocytes (NHEK), derived from chest skin, were examined. Near-confluent medium after seven days incubation of cholesteatomatous keratinocytes and NHEK was discarded and fresh medium was added. Filtrated debris medium, obtained with a milli-pore filter, lipopolysaccharides (LPS) or keratin were added to the incubation culture medium. After 48 hours, the titers of IL-1 alpha and TNF-alpha in the culture medium were measured with enzyme linked immunosorbent assay (ELISA). Debris filtrated medium showed a marked increase in IL-1 alpha, in both cholesteatomatous keratinocytes and NHEK culture, as compared with the effects of LPS, keratin and medium alone.(ABSTRACT TRUNCATED AT 250 WORDS)