EVIDENCE FOR EOSINOPHIL ACTIVATION IN EOSINOPHILIC CYSTITIS

Eosinophilic cystitis (EC) is a rare condition. Recent studies have sh own that activated eosinophils release cytotoxic cationic proteins whi ch can induce tissue damage. Moreover, in vitro studies have shown tha t interleukin-5 (IL5) is a cytokine able to attract and activate eosin ophils. The goal of this study was to detect a possible activation of eosinophils in EC using electron microscopy, in situ hybridization wit h an IL-5 RNA probe and immunochemistry with a specific anti-ILr-5 ant ibody. Using these combined methods in a typical case of EC, we found numerous activated eosinophils synthesizing and secreting IL-5 protein . IL-5 could enhance the activation of eosinophils and their cytotoxic potential in bladder tissues. This mechanism might explain the chroni city of the lesions in EC.