Circulating human leucocyte elastase levels in patients with pulmonary sarcoidosis.

In a pilot study plasma elastase concentrations were measured in 28 outpatients with pulmonary sarcoidosis. These were compared with the conventional criteria used in assessment of disease activity, namely lung function abnormalities, chest radiography changes and serum angiotensin converting enzyme (ACE) levels. An elevated plasma elastase concentration was found in 21/28 patients (mean 554 micrograms/l, range 192-1678). Of these, six had evidence of active pulmonary or cutaneous sarcoidosis and the plasma elastase level fell towards normal as the disease improved; another three had evidence of a coexistent acute phase response which might explain the raised level. Six of the remaining 12 patients had longstanding, fibrotic chest radiographic abnormalities with no apparent change during the short study period. Six of the seven patients with normal plasma elastase levels also had longstanding, apparently quiescent sarcoidosis. No correlation was found between the plasma elastase concentration and either chest radiographic score, lung function abnormalities, or serum ACE level. These findings suggest that patients with active pulmonary or cutaneous sarcoidosis have evidence of in vivo neutrophil activation. The additional finding of raised plasma elastase levels in some patients with fibrotic radiological changes implies the presence of ongoing chronic neutrophil activation, perhaps in the lung interstitium, for which further treatment might be indicated.