IL-8 IN PLEURAL EFFUSION

Interleukin-8 (IL-8) is a recently described potent chemotactic factor that may be involved in the pathogenesis of pleural effusions. To und erstand the actual mechanisms mediating the inflammatory response, cha nges in cellular components and IL-S level in pleural fluid of differe nt aetiologies were evaluated. Thirty-four patients (19 male, 15 femal e) with a mean age of 46 +/- 22 years (range 16-92) were included in t he study. Of these, 13 had tuberculous pleural effusion, seven had emp yema/parapneumonic pleural effusion, and 14 had malignant pleural effu sion (seven adenocarcinoma, three ovarian carcinoma, two lymphoma, one chronic myeloid leukaemia, and one small cell carcinoma) with positiv e cytology. Differential cell counts in the pleural fluid were obtaine d using cytocentrifuge preparations. The concentrations of IL-8 in ple ural fluid were measured by the ELISA method. Interleukin-8 was detect ed in all 34 pleural fluid samples. The serum IL-8 level was analysed only in the empyema/parapneumonic pleural effusion group The mean IL-8 levels of tuberculous, empyema/parapneumonic, and malignant pleural e ffusions were 1420 +/- 1049 pg ml(-1), 4737 +/- 2297 pg ml(-1), and 15 74 +/- 1079 pg ml(-1), respectively. The IL-8 levels in the empyema/pa rapneumonic group were significantly raised over malignant and tubercu lous groups (P<0.02). The mean pleural fluid neutrophil counts in tube rculous, empyema/parapneumonic and malignant pleural effusions were 31 5 +/- 575 cells mm(-3) 11 136 +/- 12 452 cells mm(-3), and 635 +/- 847 cells mm(-3), respectively (P<0.003). There was a significant positiv e correlation between pleural IL-8 levels and neutrophil counts (r=0.4 6, P<0.006). The levels of IL-8 in paired samples of serum and pleural fluid in the empyema/parapneumonic effusion group were compared, and the concentration of IL-8 was higher in the pleural effusion than seru m (means, 4737 +/- 2297 pg ml(-1) and 130.0 +/- 62.5 pg ml(-1), respec tively, P<0.03). There was a significant negative correlation between IL-8 concentrations in serum and pleural fluid (r=-0.80, P<0.03). This data suggests that production of IL-8 in pleural effusion may play a key role in initiation and maintenance of inflammatory reactions, espe cially in empyema/parapneumonic pleural effusions. II may offer the ba sis for introduction of novel anti-inflammatory agents in treatment.