INTERLEUKIN-6 AND ITS RELATIONSHIP TO CLINICAL-PARAMETERS IN PATIENTSWITH MALIGNANT PLEURAL MESOTHELIOMA

The relationship between interleukin 6 (IL-6) levels and clinical para meters was studied in 25 patients with malignant pleural mesothelioma. The serum levels of IL-6, C-reactive protein, alpha(1)-acid glycoprot ein and fibrinogen were significantly higher in mesothelioma than in l ung adenocarcinoma with cytology-positive pleural effusion. Serum IL-6 levels correlated with the levels of the acute-phase proteins. We dem onstrated a high incidence of thrombocytosis (48%) and a significant c orrelation between platelet count and the serum IL-6 level. The level of IL-6 in the pleural fluid of patients with mesothelioma was signifi cantly higher than in the pleural fluid of patients with adenocarcinom a, and was about 60-1400 times higher than in the serum. However, even higher levels of IL-6 in the pleural fluid and of thrombocytosis were found in patients with tuberculous pleurisy. These results indicate t hat large amounts of IL-6 from the pleural fluid of patients with meso thelioma leak into the systemic circulation and induce clinical inflam matory reactions. These profiles are not specific to mesothelioma as s imilar profiles are found in patients with tuberculous pleurisy. Howev er, the detection of a markedly increased level of IL-6 in pleural flu id argues against a diagnosis of adenocarcinoma.