Adenosine deaminase activity and fibronectin levels in bronchoalveolar lavage fluid in sarcoidosis and tuberculosis.

We have studied Adenosine Deaminase (ADA) activity and Fibronectin (FN) levels in Bronchoalveolar Lavage Fluid (BALF) from 50 patients with Sarcoidosis (15 active, 35 non active) and from 24 patients with Pulmonary Tuberculosis in order to evaluate relationships between both ADA and FN in BALF and alveolitis data. BALF ADA activity increases in active sarcoidosis as well as in tuberculosis, as a result of activation, differentiation and proliferation of blood-derived mononuclear alveolar cells. In sarcoidosis this hypothesis is supported by the significant positive correlation observed between ADA activity and both the number of alveolar CD4+ lymphocytes and the number of alveolar lymphocytes bearing activation antigens (CD25 and VLA-1). BALF FN levels increase, showing highest values in active sarcoidosis. ADA and FN elevation in BALF from active sarcoidosis patients could be suggested as additional markers of disease activity. Highest BALF ADA/Albumin ratio observed in pulmonary tuberculosis patients suggests an increased local production and differentiates pulmonary tuberculosis from active sarcoidosis. Increased FN/Albumin ratio observed in non active sarcoidosis appears to be related to a similar mechanism during the reparative process following granulomatous inflammation.