Evaluation of Cytokines in Pleural Fluid for the Differential Diagnosis of Tuberculous Pleurisy

The present study aims to test reliability of interferon gamma (IFNγ) as a diagnostic marker for tuberculous pleurisy. In this study, interleukin-8 (IL-8), tumour necrosis factor α (TNF-α) and interferon gamma (IFN-γ) were therefore compared with adenosine deaminase (ADA) in exudative pleural effusion of inflammatory, malignant and tuberculous origin to determine their diagnostic value and whether either or all of them could be helpful in the differential diagnosis of tuberculous pleural effusion. Subjects and methods: This study included 11 patients with inflammatory, 13 patients with malignant, and 15 patients with tuberculous effusion matched for age and sex. Estimation of Pleural fluid levels of ADA, IL-8, TNF-α and IFN-γ. Results: Pleural fluid levels of ADA, IL-8, TNF-α and IFN-γ in the tuberculous group were significantly higher than in the malignant group. Also the levels of pleural fluid ADA, TNF-α and IFN-γ in the tuberculous group were significantly higher than in the inflammatory group. Analysis of receiver operating characteristic (ROC) curves, to evaluate the utility of the various parameters, demonstrates values for the area under the curve (AUC) of 0.702, 0.897, 0.927, and 0.987, respectively for IL-8, TNF α , ADA, and IFN γ. The sensitivity and specificity with IFN γ were 93% and 100%,respectively, which were superior to those for ADA(sensitivity: 80% and specificity:91%), TNFα (sensitivity: 86% and specificity:91% ) and IL-8 (sensitivity: 46% and specificity: 72%) . Conclusions: Levels of the pleural fluid cytokines examined in this study were higher in the tuberculous than in the two other groups. Our data suggested that IFNγ being shown to be especially very reliable, is a non -invasive and useful marker for diagnosis of tuberculous pleurisy, with clear advantages over ADA.