The aim of this study was to explore the presence of interleukin (IL)-16 in pleural effusions, the correlation between IL-16 levels and cytological parameters, as well as the chemoattractant activity of IL-16 on CD4+ T-lymphocytes.Total nucleated cell and differential counts, and IL-16 concentrations in the pleural effusion from 32 patients with tuberculous pleurisy and 30 patients with lung cancer were determined. Threecolour flow cytometry was performed to determine T-lymphocyte subsets in cell pellets of pleural effusion. The chemoattractant activity of IL-16 for CD4+ T-lymphocytes was also analysed.The levels of IL-16 were significantly higher in tuberculous than in malignant effusions. However, IL-16 levels could not be used for diagnostic purposes due to significant overlap between the two groups. Positive correlations were found between the IL-16 levels and CD4+ Tcells, and pleural fluid was chemotactic for CD4+ T-cells in vitro. Intrapleural administration of IL-16 to patients produced a marked progressive influx of CD4+ T-cells into the pleural space.Compared with malignant pleural effusion, interleukin-16 appeared to be increased in tuberculous pleural effusion. Interleukin-16 levels were positively related to the numbers of CD4+ T-cells, and interleukin-16 could directly induce CD4+ T-cell infiltration into the pleural space.

The aim of this study was to investigate the presence of epithelial neutrophilactivating peptide (ENA)-78 in pleural effusions, as well as the chemoattractant activity of pleural ENA-78 on neutrophils.Pleural effusion and serum samples were collected from 75 patients who presented to the respiratory institute (19 with malignant pleural effusion, 21 with tuberculous pleural effusion, 18 with infectious pleural effusion and 17 with transudative pleural effusion). The concentrations of ENA-78, myeloperoxidase and neutrophil elastase were determined, and the chemoattractant activity of ENA-78 for neutrophils both in vitro and in vivo was also observed.The concentrations of ENA-78, myeloperoxidase and neutrophil elastase in infectious pleural effusion were significantly higher than those in malignant, tuberculous and transudative groups, respectively (all p,0.01). Infectious pleural fluid was chemotactic for neutrophils in vitro and anti-ENA-78 antibody could partly inhibit these chemotactic effects. Intrapleural administration of ENA-78 produced a marked progressive influx of neutrophils into pleural space.Compared with noninfectious pleural effusion, ENA-78 appeared to be increased in infectious pleural effusion. Our data suggested that ENA-78 was able to induce neutrophil infiltration into pleural space and might be responsible for pleural neutrophil degranulation.