Lavage versus serum measurements of lysozyme, angiotensin converting enzyme and other inflammatory markers in pulmonary sarcoidosis.

The aim of this study was to explore whether amounts of angiotensin converting enzyme (ACE) and lysozyme produced within the lungs correlate more closely than serum levels of these enzymes, or other inflammatory markers, with chest radiographic profusion scores, lung function and therapy response in patients with pulmonary sarcoidosis. We have studied 25 patients, and levels in bronchoalveolar lavage (BAL) were used to determine "local" enzyme production by reference to serum and lavage albumin. Before treatment, serum lysozyme levels were elevated in more patients (80%) than serum ACE levels (40%). They also gave the best overall correlation with clinical measurements prior to treatment and falls in serum lysozyme closely parallelled improvement in lung function (transfer factor for carbon monoxide (DLCO)) on therapy. The only other markers showing significant correlations with disease severity were lavage neutrophil counts per ml and "local" ACE measurements prior to treatment. The value of pre-treatment levels of the different inflammatory markers in predicting response to corticosteroid therapy was explored and the only significant finding was that BAL lymphocyte percentages and numbers.ml-1 were initially higher in patients with lower post-treatment chest X-ray scores (p less than 0.01 and p less than 0.05, respectively). We conclude that serum lysozyme levels appear to be a more useful marker of overall disease activity in sarcoidosis than measurements of other inflammatory markers. However, BAL lymphocyte counts were the best predictive marker of radiographic response to corticosteroids.