QUANTITATIVE-ANALYSIS OF INTERLEUKIN-1-ALPHA GENE-EXPRESSION IN MIDDLE-EAR CHOLESTEATOMA

Regardless of its origin, cholesteatoma is characterized by the presen ce of a keratinizing epithelium with an hyperproliferative behavior le ading to a very important bone resorption. Previous studies have demon strated overexpression of interleukin-1 (IL-1) protein in middle ear c holesteatoma by immunohistochemistry and enzyme-linked immunosorbent a ssay, suggesting a significant role for IL-1-alpha. In this study, the presence of IL-1-alpha messenger ribonucleic acid (mRNA) was quantifi ed by in situ hybridization on frozen sections (n=10) and by computer- assisted image analysis, Human skin obtained from the external ear can al (n=10) was used as the control. A higher percentage of cells hybrid ized for the antisense probes IL-1-alpha mRNA was found in cholesteato ma epithelium. Furthermore, keratinocytes of the suprabasal cell layer s were also found to contain specific hybridizations. Some cells in ch olesteatoma stroma also contained IL-1-alpha mRNA transcripts, The res ults of this study confirm the central role of IL-1-alpha in the epith elium hyperproliferation and bone resorption observed in middle ear ch olesteatoma.