IL-6 in malignant pleural effusions and its augmentation by intrapleural instillation of IL-2.

The levels and activities of endogenous IL-6 in malignant pleural effusions due to lung cancer before and during daily intrapleural instillations of recombinant IL-2 were examined by enzyme immunoassay and bioassay using an IL-6-dependent murine hybridoma cell line MH60.BSF2. Before therapy, malignant pleural effusions contained various levels of IL-6. Daily intrapleural instillation of recombinant IL-2 for treatment of malignant pleurisy resulted in significant augmentation of the levels and activities of IL-6 in the pleural effusions. On fractionation of the pleural effusion by chromatography, one major peak of material with a mol. wt of 24 kD showed IL-6 activity. In contrast, no significant level of tumour necrosis factor-alpha or IL-1 beta was detectable in pleural effusions before or during local IL-2 therapy. These data suggest that IL-2 is an important regulatory factor of secondary IL-6 production.