Induction of macrophage exudation in the inner ear by OK432 treatment

OK432, a heat- and penicillin-treated lyophilized powder of a low virulent Su strain of Streptococcus pyogenes, was injected into the perilymphatic sp ace of guinea pigs in order to determine the kinetics of exudation of infla mmatory cells into the cochlea over a 7-day period. OK432 induced exudation of many neutrophils and Asialo GM(1)-positive cells into the scala tympani . The numbers of these cells peaked on the first day after OK432 treatment, and then gradually decreased. Four days after treatment very Few of either of these types of cells were observed in the scala tympani. Asialo GM(1)-p ositive cells were confirmed to be activated macrophages. In ears treated w ith physiological saline or with the additive included in OK432 in control studies, no notable changes in the inner ear were recognized. These finding s suggest that the inner ear can undergo induction of macrophage rapidly ex udation by OK432 treatment as has previously been observed for other organs .