Mast cells are known to play an important role in the pathogenesis of interstitial pulmonary fibrosis, but their participation in the pathogenesis of bronchiolitis obliterans organizing pneumonia is less well known. We examined the zonal distribution of mast cells in 22 patients with bronchiolitis obliterans organizing pneumonia by using a monoclonal antibody targeting mast cell tryptase. Cases of interstitial pulmonary fibrosis (n = 5) and normal lung tissue (n = 12) were used for comparative analysis. The 22 patients (nine men, 13 women) included seven patients with constrictive bronchiolitis after lung transplantation. Mast cells were counted by two observers in three pulmonary zones. Zone 1, the most peripheral area, was defined as an area of 10 high-power fields immediately adjacent to zone 2, which encompassed a circular area located within one high-power field from the bronchial basement membrane. Zone 3 was located within the intraluminal fibrous plugs. The study showed a trizonal distribution of mast cells in bronchiolitis obliterans organizing pneumonia and bizonal mast cell distribution in constrictive bronchiolitis. This difference is most probably related to the absence of intraluminal plugs in constrictive bronchiolitis and is likely to be nonsignificant. Thus bronchiolitis obliterans organizing pneumonia and constrictive bronchiolitis demonstrated an essentially similar peribronchiolar mast cell distribution. However, interstitial pulmonary fibrosis demonstrated a greater increase of mast cells as compared with either bronchiolitis obliterans organizing pneumonia or constrictive bronchiolitis. This suggests that mast cells play a role in the fibrogenesis of both airway and nonairway fibrosis. However, mast cell counts alone did not appear to explain the well-known morphologic differences between bronchiolitis obliterans organizing pneumonia and constrictive bronchiolitis.
- Bronchiolitis obliterans organizing pneumonia (BOOP)
- Constrictive bronchiolitis (CB)-Interstitial pulmonary fibrosis (IPF)
- Mast cells
ASJC Scopus subject areas
- Medical Laboratory Technology