Mast cells in bronchoalveolar lavage fluid of patients with interstitial lung diseases

Mast cells play an important role in tissue inflammation, fibrosis and remodelling. They are found in bronchoalveolar lavage fluid (BAL) of healthy persons only in small numbers. We investigated the number of mast cells in interstitial lung diseases and analysed our data for correlations with clinical parameters, cellular and non-cellular parameters of BAL. We found following counts of mast cells in % of total BAL cells: Sarcoidosis (n = 123); 0.22 +/- 0,04 %, idiopathic pulmonary fibrosis (IPF) (n = 35); 0.39 +/- 0.47 %, cryptogenic organising pneumonia (COP) (n = 27); 2.05 +/- 2.19 %, hypersensitivity pneumonitis (HP) (n = 24); 1.02 +/- 1.05 %, rheumatoid lung (n = 20); 0.21 +/- 0.21 %, respiratory bronchiolitis-associated interstitial lung disease (RBILD) (n = 11); 0.16 +/- 0.29 %) and control group (n = 16); 0.06 +/- 0.16 %. Compared to controls mast cells were increased in COP (p < 0.001) and HP (p < 0,01). Correlation analysis showed that an increased mast cell count correlated with: Higher age (sarcoidosis (p = 0.03); smaller vital capacity (sarcoidosis (p = 0.01)), smaller FEV 1 (sarcoidosis (p = 0.04), RBILD (p = 0.04)); higher alkaline phosphatase in BAL (sarcoidosis (p = 0.004), HP (p = 0.02), COP (p = 0.04); higher albumin level in BAL (sarcoidosis (p = 0.000), IPF (p = 0.003); higher cell counts in BAL (sarcoidosis (p = 0.013), COP (p = 0.04)); lower portion of macrophages in BAL cells (sarcoidosis (p = 0.001), HP (p = 0.02), COP (p = 0.02)); higher portion of lymphocytes in BAL cells (sarcoidosis (p = 0.03)); higher portion of neutrophils in BAL cells (sarcoidosis (p = 0.007)); higher portion of eosinophils in BAL cells (sarcoidosis (p = 0.001), HP (p = 0.006)). Correlations to smoking history in pack years and to lymphocyte surface markers CD3, CD4, CD8 were not found. In conclusion comparing different interstitial lung diseases we found significantly increased mast cell counts in COP and HP. Moreover there were correlations of increased mast cell counts with more intensive alveolitis and exudation.