Correlation Between Polymorphonuclear Leukocyte Counts and Levels of Tumor Necrosis Factor-a in Pleural Fluid of Patients with Parapneumonic Effusion

High concentrations of tumor necrosis factor-a (TNF), as well as excess of polymorphonuclear leukocytes (PMNs), are present in pleural fluid of patients with complicated parapneumonic effusion (CPPE). Several studies have shown that PMNs are capable of secreting TNF. However, the correlation between levels of TNF and PMN counts in pleural fluid of patients with parapneumonic effusion has not been previously evaluated. This study was undertaken to evaluate this correlation. Using a commercially available high sensitivity ELISA kit, levels of TNF were measured in pleural fluid of patients with UCPPE (n = 22), and CPPE (n = 14), and were compared with PMN count in pleural fluid of these patients. The mean ± SD values of pleural fluid TNF and PMN count in the UCPPE group the group were 10.15 ± 6.48 pg/mL and 3452 ± 2878 cells/mm3, respectively, and in the CPPE group the values were 55.51 ± 29.49 pg/mL and 25261 ± 11733 cells/mm3, respectively. Levels of pleural fluid TNF and PMN counts in the CPPE group were significantly higher than in the UCPPE group (p <0.0001). A significant correlation was found between levels of pleural fluid TNF and PMN counts in the CPPE group (r = 0.57, p = 0.03) and also in the UCPPE group (r = 0.44, p = 0.04). The results of this study indicate that in pleural fluid of patients with UCPPE or CPPE, levels of TNF correlate positively with PMN counts, and PMNs might be an important source of TNF production in pleural fluid of these patients, particularly in those with CPPE.