Activation of neutrophils, eosinophils, and lymphocytes in the lower respiratory tract in Wegener's granulomatosis

Levels of cell products released by neutrophils, eosinophils and lymphocytes were measured in the bronchoalveolar lavage fluid (BALF) of 19 patients with pulmonary active Wegener's granulomatosis (WG) to assess in vivo the magnitude of cellular activation at sites of active disease. Measurements included the BAL cell profile and BALF levels of myeloperoxidase (MPO), free proteinase 3 (fPR3), complexes of PR3 and α1-antitrypsin (PR3/α1-AT), eosinophil cationic protein (ECP), peroxidase activity (PEROX), and soluble interleukin-2 receptor (sIL-2R). Six patients also underwent a repeat examination after immunosuppressive treatment. Pulmonary active WG was found to be associated with elevated MPO, PEROX, ECP, and sIL-2R levels in BALF. Only trace amounts of fPR3 were detected, the bulk of PR3 being found in PR3/α1-AT complexes. Clinically effective treatment depressed BAL neutrophil counts and reversed elevated levels of MPO and PEROX but had an inconsistent effect on the BAL lymphocyte count and the sIL-2R level. In conclusion, the elevated levels of extracellular MPO and PEROX at a site of active disease and the correlation between these and clinical disease activity support the view that neutrophils are indeed an important effector cell population in WG lung disease. The present data also suggest that oxidative injury is an important aspect of neutrophil-mediated lung injury, whereas it remains unresolved whether the low levels of fPR3 in the BALF adequately reflect the situation at inflammatory tissue sites.