Background: The aim of our study was to compare clinical and BAL features of patients with bronchiolitis obliterans organizing pneumonia (BOOP) with those of patients with usual interstitial pneumonia (UIP) and control subjects.
Patients and methods: This study reports on 14 patients with idiopathic BOOP. Diagnosis was made upon histology. Lung function tests were mostly normal. Chest X-ray and CT showed always a patchy consolidation, often associated with ground glass pattern. BAL was performed for cytology and for ELISA assessment of several cytokines (IL8, ILI0, IL12, gamma-interferon, IL 18, monocyte chemoattractant protein- 1).
Results: Cytology of BAL in BOOP showed a pattern of lymphocytic alveolitis (Lymphocytes: 0.36 x 10(6)/ml) associated with an increase in neutrophil and eosinophil counts (0.13 and 0.04 x 10(6)/ml respectively). Mean BALf levels in pg/ml of MCP-1, IL12 and IL18 were significantly increased in BOOP with respect to controls and UIP patients, while in UIP patients only a significant increase of IL8, MCP-1 and IL18 with respect to controls was detected. In addition, BALf levels of IL10, an anti-inflammatory cytokine, were significantly higher in BOOP patients with respect to controls and UIP patients.
Conclusion: These findings are consistent with a marked degree of macrophage and lymphocyte activation in BOOP with an expansion of T helper-1 response. The concomitant increase of IL10 could be related to a limitation of the inflammatory process and the fibrotic evolution typical of this clinical picture.