Adenosine deaminase activity and lysozyme levels in bronchoalveolar lavage fluid in patients with pulmonary tuberculosis

SETTING: The estimations of adenosine deaminase (ADA) activity and lysozyme (LYS) levels in pleural fluid have been proved useful tools in the diagnosis of tuberculous pleural effusions. Little is known about their usefulness when estimated in bronchoalveolar lavage fluid (PALE). OBJECTIVE: TO evaluate whether both ADA activity and LYS levels in BALE could be employed in the diagnosis of pulmonary tuberculosis, and especially in active but acid fast bacilli (AFB) smear negative cases. DESIGN: ADA activity and LYS levels were determined in BALE and serum obtained on the same day in 28 patients with tuberculosis, 21 with interstitial lung diseases, 14 with lung cancer and 13 with infectious diseases. RESULTS: Patients with pulmonary tuberculosis had significantly higher ADA activity in BALF than patients with non-tuberculous lung diseases (P < 0.001). High BALF ADA activity in pulmonary tuberculosis patients suggests increased local production. In contrast, in this group of patients BALE LYS levels were not significantly higher than in the other groups of patients, but were in the group with interstitial lung diseases. CONCLUSION: BALF ADA activity seems to be a useful tool in the differentiation of tuberculosis from other lung diseases. Its estimation can be restricted to the detection of cases with AFB negative smears.