OBJECTIVE: As soluble interleukin-2 receptor (sIL-2R) is a marker of T-lymphocyte activation, we sought to determine whether its measurement in pleural fluid is diagnostically useful in tuberculous pleurisy. DESIGN: We compared the concentrations of sIL-2R in pleural samples of 23 patients with tuberculous pleurisy and 109 patients with non-tuberculous effusions (34 malignant, 34 parapneumonic, 27 transudates and 14 miscellaneous). sIL-2R was measured by a commercial ELISA test and its performance was evaluated using receiver operating characteristic (ROC) analysis. RESULTS: The mean values of pleural sIL-2R were 9179 U/mL in patients with tuberculous pleurisy vs 3664 U/mL in patients with malignancy, 2603 U/mL in patients with parapneumonic effusions, 1016 U/mL in patients with transudates, and 1906 U/mL in patients with miscellaneous diseases (P < 0.0001). A ROC curve identified the best cut-off at 4700 U/mL, yielding measures for sensitivity (0.91), specificity (0.94) and accuracy (0.94). CONCLUSIONS: The results of this pilot study suggest that pleural sIL-2R appears to be clinically useful for differentiating between tuberculous and non-tuberculous pleural effusions.
OBJECTIVE: As soluble interleukin-2 receptor (sIL-2R) is a marker of T-lymphocyte activation, we sought to determine whether its measurement in pleural fluid is diagnostically useful in tuberculous pleurisy. DESIGN: We compared the concentrations of sIL-2R in pleural samples of 23 patients with tuberculous pleurisy and 109 patients with non-tuberculous effusions (34 malignant, 34 parapneumonic, 27 transudates and 14 miscellaneous). sIL-2R was measured by a commercial ELISA test and its performance was evaluated using receiver operating characteristic (ROC) analysis. RESULTS: The mean values of pleural sIL-2R were 9179 U/mL in patients with tuberculous pleurisy vs 3664 U/mL in patients with malignancy, 2603 U/mL in patients with parapneumonic effusions, 1016 U/mL in patients with transudates, and 1906 U/mL in patients with miscellaneous diseases (P < 0.0001). A ROC curve identified the best cut-off at 4700 U/mL, yielding measures for sensitivity (0.91), specificity (0.94) and accuracy (0.94). CONCLUSIONS: The results of this pilot study suggest that pleural sIL-2R appears to be clinically useful for differentiating between tuberculous and non-tuberculous pleural effusions.