Elastase activity of bronchoalveolar cells in advanced pulmonary sarcoidosis

Elastase activities were investigated in bronchoalveolar lavage (BAL) cells from healthy controls (C, n = 8) and patients with untreated mediastinopulmonary sarcoidosis at different stages: I (n = 5), II (n = 7), IIIA (n = 3), IIIB (n = 4). Elastase activities (EA and ELA) were measured against a synthetic substrate, succinyl-trialanine-paranitroanilide (SLAPN) and radiolabelled ligamentum nuchae 3H insoluble elastin (specific radioactivity 3.7 MBq.mg-1). A significant increase of ELA of BAL cells was observed in patients (S III), in particular those exhibiting fibrotic roentgenographic patterns and a higher number of polymorphonuclear cells. On the contrary, EA of BAL cells showed no variation between different stages of sarcoidosis. ELA was never detected in the macrophage culture medium and appeared to be mainly associated with non-adherent macrophages, whereas EA appeared to be preferentially associated with adherent macrophages. The inhibitory profiles of ELA and EA were investigated using general proteinase inhibitors and also compounds interacting specifically with leucocyte elastase. ELA was mainly due to a serine protease, which has a sensitivity to inhibitors similar to leucocyte elastase and is increased in advanced stages of sarcoidosis. EA appears to be only slightly modified, if at all, in sarcoidosis and is probably related to the action of both a serine protease and a metalloenzyme. Thus, only ELA yields diagnostic information concerning stage III of sarcoidosis associated with a fibrotic or bullous roentgenographic pattern.