Analysis of pleural fluid in idiopathic spontaneous pneumothorax; correlation of eosinophil percentage with the duration of air in the pleural space

Pleural fluid analysis was performed in patients with idiopathic spontaneou s pneurnothorax. The objective of the study was to define the cell differen tiation, and part of the cytokine profile, in relation to the duration of p neumothorax. In the 23 consecutive patients (19 men, mean age 34.2 years, 17 smokers), p leural fluid was obtained immediately after chest tube drainage (n=6), or d uring thoracoscopy (n=17). Cytospins were carried out, and supernatant anal ysis of the different cytokines was performed using sandwich ELISA. All con centrations were corrected for dilution. The duration of the pneumothorax was correlated with the rise in eosinophil percentage (r=0.81, P<0.00001) in pleural fluid. RANTES, platelet-activati ng factor (PAF), and monocyte chemotactic protein-1 (MCP-I) were detectable but no relationship with eosinophils or duration of the pneumothorax was f ound. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interlu ekin-8 (IL-8) were not detectable. Interleukin-5 (IL-5) concentration corre lated with the eosinophil concentration (r=0.84, P=0.037) and the eosinophi l percentage (r=0.68, P=0.005) in the pleural fluid. Idiopathic spontaneous pneumothorax causes a time-related rise in the eosin ophil percentage in the pleural space, which correlates with the level of I L-5.