ADA and chronic obstructive pulmonary disease: In a study by Kayacan et al. [8], ADA level in BAL fluids of pulmonary TB patients, non-TB lung disease patients (like interstitial lung disease, lung cancer, pneumonia, and COPD) and controls was 3.1 ± 2 IU/L, 0.4 ± 0.5 IU/L, and 0.2 ± 0.4 IU/L, respectively, (P < 0.001).