Studies on the pathogenesis of sarcoidosis

Part I. Studies on bronchoalveolar lavage fluid

Abstract

The present study was designed to investigate the local immunity and pathological state of sarcoidosis. Cell populations and angiotensin converting enzyme (ACE) activity were examined in the fluid obtained by bronchoalveolar lavage (BAL) of 28 patients with sarcoidosis and 31 healthy volunteers.
The proportion and number of lymphocytes in BAL fluid were significantly higher in patients with sarcoidosis than in healthy volunteers. Furthermore, the number of T lymphocytes and B lymphocytes were increased. The cell number in BAL fluid was also higher in non-smokers with sarcoidosis than in healthy non-smokers. The ACE activity in bronchoalveolar lavage fluid (BALF-ACE activity) was highly elevated in patients with sarcoidosis as compared with healthy volunteers and correlated with the number of macrophages in BAL fluid of non-smokers with sarcoidosis (r=0.474, p<0.05). The elevation of BALF-ACE activity was suggested to be due to alveolar macrophages. In smokers with sarcoidosis and healthy volunteres who smoked, the number of cells and macrophages in BAL fluid was markedly increased, while the number of lymphocytes was not affected by smoking.
It was concluded that lymphocytes, mainly T lymphocytes which play a major role in forming granuloma, were incerased in patients with sarcoidosis and that high BALF-ACE activity was probably due to activated macrophages and epithelioid cells in sarcoid granulomas of the lung.