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In this work, using bronchoalveolar lavage fluids (BALF), we demonstrated the presence of complement within airways by assaying hemolytic activity of the whole classical pathway (CH50) and by measuring the complement component C2 (C2H50). Patients with sarcoidosis, patients with idiopathic pulmonary fibrosis (IPF), and healthy control subjects were compared. No CH50 activity was found in BALF from healthy control subjects (n = 9), but some activity (mean, 20 CH50) was associated with IPF (n = 7). Complement activities ranged from 40 to 554 CH50 in patients with sarcoidosis (n = 27). During the treatment, complement activity decreased in BALF from the few patients in our series who received corticotherapy. C2 hemolytic activity was detected in BALF from the normal control group (in the absence of CH50 activity). In the sarcoidosis and IPF groups when CH50 was present, the variations in the C2/CH50 ratio were studied. The high ratio observed in BALF from patients with sarcoidosis and a chronic derangement of alveolar structure suggests either an increased C2 production or an alternative complement pathway (C2-independent) activation within their lungs.

Fifty-two bronchoalveolar lavages (BAL) were performed in order to investigate 46 episodes of pneumonitis that occurred after allogeneic bone-marrow transplantation. No complications have been attributed to this procedure. A specific etiologic diagnosis was obtained in 24 of 46 episodes (52%) by 26 of 52 BAL (50%). Cytomegalovirus (CMV), diagnosed by the presence of typical inclusions, was the pathogen most frequently identified by BAL (13 of 46 episodes) and was associated with other causes of pneumonia in 4 patients. The other causes of pneumonitis diagnosed by BAL were: giant-cell pneumonia: 1, aspergillosis alone: 3, Pneumocystis carinii: 1, Hemophilus influenzae: 3, isolated pulmonary hemorrhage: 3. One false negative (aspergillosis, n = 1) was diagnosed at autopsy. The overall mortality rate of these episodes was 24%. Thus, BAL appears to be a rapid and reproducible diagnostic method for monitoring pneumonitis in grafted patients, particularly CMV pneumonitis, and may avoid the need for surgical biopsy.