Evaluation of cytokines in pleural fluid for the differential diagnosis of tuberculous pleurisy

ABSTRACT

To test reliability of interferon gamma [IFN-gamma] as a diagnostic marker for tuberculous pleurisy. In this study, interleukin-8 [IL-8], tumour necrosis factor alpha [TNF-alpha] and interferon gamma [IFN-gamma] were therefore compared with adenosine deaminase [ADA] in oxidative 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. Setting: Medical Biochemistry and Internal Medicine Departments, Faculty of Medicine, Cairo University Subjects: This study included 11 patients with inflammatory, 13 patients with malignant, and 15 patients with tuberculous effusion matched for age and sex. Main outcome measures: Pleural fluid levels of IL-8, TNF-alpha, IFN-gamma and ADA. Pleural fluid levels of ADA, IL-8, TNF-alpha and IFN-gamma in the tuberculous group were significantly higher than in the malignant group. Also the levels of pleural fluid ADA, TNF-alpha and IFN-gamma 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-alpha, ADA, and IFN-gamma. The sensitivity and specificity with IFN-gamma were 93% and 100%,respectively, which were superior to those for ADA [sensitivity 80% and specificity 91%], TNF-alpha [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 IFN-gamma being shown to be especially very reliable, is a non -invasive and useful marker for diagnosis of tuberculous pleurisy, with clear advantages over ADA