TUMOR-NECROSIS-FACTOR DURING EXPERIMENTAL LIPOPOLYSACCHARIDE-INDUCED OTITIS-MEDIA

Studies in our laboratory and others have indicated that endotoxin is present in a high percentage of human middle ear effusions, including those that are culture negative. Endotoxin has been identified as one of the most potent inducers of tumor necrosis factor (TNF), but this r elationship has not been investigated in regard to the pathogenesis of otitis media, The purpose of this study was to determine whether endo toxin induces the production of TNF in the middle ear. Otitis media wa s induced in chinchillas by the injection of isolated lipopolysacchari de and middle ear fluids (MEFs) and serum harvested and assayed for TN F content by means of a cytolytic assay using L-929 cells and the Cell Titer 96 assay (Promega, Madison, WI). The MEF pools' TNF concentrati on ranged from 200 to 1,100 pg/mL MEF. Serum pools did not contain any detectable TNF. The results of the present study suggest that endotox in induces TNF production locally in the middle ear cleft, which may c ontribute to the pathogenesis of otitis media via any number of establ ished inflammatory pathways.