Oncostatin M in bronchoalveolar lavage correlates with the severity of sarcoidosis

Background: Recent studies have shown that oncostatin M (OSM) might have a role in T cell-mediated inflammatory processes in which mast cells are also involved. Patients with severe sarcoidosis might develop fibrotic changes in the lung. We assessed whether there was a correlation between mast cells expressing OSM in bronchoalveolar lavage (BAL) and the severity of sarcoidosis. Patients and methods: Twelve consecutive patients with new diagnosis of sarcoidosis were eligible for the study. All underwent complete lung function tests, angiotensin converting enzyme (ACE), and bronchoscopy that included BAL and biopsies. Cytospins of BAL were prepared. All samples were incubated with the primary antibody rabbit anti-human c-kit, CD117 and stained for total mast cell count. The mouse anti-human OncostatinMwas applied and activated mast cells were counted. Clinical sarcoidosis parameters including ACE and lung functions were correlated with mast cells in BAL, as well as with OSM positive mast cells. Results: FEV1% was correlated with the percentage of activated mast cells, as well as with the percentage of OSM positive mast cells (r=0.61, p=0.033, 95% CI: 0.06-0.87; r=0.58, p=0.04, 95% CI: 0.015-0.86, respectively). FVC and FEV1/FVC correlated with activated mast cells (r=0.58, p=0.05; r=0.63, p=0.028, respectively). Conclusions: Direct correlation was found between clinical parameters including lung function tests (FEV1 and FVC) and OSM secretion from mast cells in patients with sarcoidosis. These findings suggest that mast cells and OSM have a role in sarcoidosis. Further studies to confirm these preliminary results are suggested.