Role of Interferon-Gamma in Bronchoalveolar Lavage Fluid on Distinguishing Active Pulmonary Tuberculosis from other Pulmonary Diseases

Tuberculosis is a global public health problem in the world. Microscopy of sputum smears is the most widely used method for diagnosing tuberculosis. However, many patients are smears negative for acid fast bacilli. Regarding the pathogenesis of the disease, the effectiveness of interferon-γ (IFN-γ) in bronchoalveolar fluid was investigated for the disease diagnosis. This descriptive study was performed at the Ali Ibn-e-Abitaleb hospital, Zahedan, between 2010 and 2012, to assess the role of IFN-γ level in bronchoalveolar lavage in distinguishing tuberculosis from other pulmonary diseases. In patients who required fiberoptic bronchoscopy as indicated, bronchoalveolar lavage was analyzed in terms of smear acid-fast staining and cytology. The participants were divided into TB patients group (the BK smear of bronchoalveolar fluid or the culture was positive) and pulmonary non-TB patients group (the smear was negative). Yet non-TB disease was definitively diagnosed by other means, as well. The fluid in each group was examined in terms of IFN-γ. Then, Mean IFN-γ levels in BALF were measured in these groups and then compared with each other. Eighty eight patients were enrolled in the study among which, 31 cases had TB and 57 patients suffered from pulmonary non-TB disease. Mean IFN-γ was 2.85±4.17 pg/mL in pulmonary TB patients and 2.21±1.21 pg/mL in pulmonary non-TB patients. Lack of significant differences between the two groups in IFN-γ indicate that this factor is not suitable for diagnosis of tuberculosis and differentiating it from other pulmonary diseases.