Among several biological markers measured in pleural effusions, interferon (IFN)-gamma is the most sensitive and specific to diagnose pleural tuberculosis (TB). However the measurement of the IFN-gamma level in pleural fluid is not always available. The Quantiferon-TB test (QFT) is a whole-blood IFN-gamma assay for the recognition of cell-mediated immune response to Mycobacterium tuberculosis infection. We investigated whether QFT in whole-blood and pleural effusion is helpful to diagnose pleural TB.
QFT was performed with the pleural fluid and whole blood of patients with pleural effusion. We also measured pleural fluid adenosine deaminase (ADA) level and did pleural biopsy. Pleural TB was diagnosed if biopsy result shows chronic granulomatous inflammation.
Of the 28 patients with pleural effusion, 20 patients were due to TB. The QFT of whole blood was positive in 12 out of 20 pleural TB patients, and sensitivity was 60.0%. The QFT of pleural fluid was positive in 8 out of 18 pleural TB patients. When we set cutoff value for ADA level 40 IU/L, the sensitivity was 85% to detect pleural TB.
The sensitivity of the QFT in whole blood and pleural effusion was lower than the measurement of the pleural fluid ADA level.
Our result demonstrates that the QFT in whole blood and pleural fluid is not helpful to diagnose pleural TB in the region where TB prevalence is high.
Dookyung Yang, None.