[Eosinophil colony stimulating activity induced by administration of interleukin-2 into the pleural cavity of patients with malignant pleurisy].

Systemic administration of interleukin-2 (IL-2) in patients with malignant diseases induces peripheral eosinophilia. In the present study, to clarify the mechanisms of eosinophilia induced by IL-2, we examined the changes in the number of eosinophils and in eosinophil colony stimulating activity (Eo-CSA) in the pleural fluid of six patients with malignant pleurisy caused by lung cancer or malignant mesothelioma, during and after intrapleural administration of IL-2. Results showed that intrapleural administration of IL-2 induced marked eosinophilia in the pleural fluid and mild eosinophilia in the peripheral blood, and that during IL-2 administration, marked Eo-CSA appeared in the pleural fluid before increase in the number of eosinophils. The Eo-CSA seemed to be a polypeptide or protein because it was trypsin-sensitive and had a molecular weight of 40-60 kDa.