The clinical significance of mast cell tryptase in bronchial alveolar lavage fluid in interstitial lung diseases]

Mast cell tryptase plays an important role in fibrosis. Tryptase levels in bronchial alveolar lavage fluid (BALF) from patients with interstitial lung diseases are frequently increased, but little is known of the clinical significance. The study population consisted of 93 patients 38 with sarcoidosis, 23 with collagen vascular disease (CVD), and 32 with idiopathic pulmonary fibrosis (IPF)]. BALF tryptase levels were measured with a newly developed B12 antibody-fluoroimmunocap method (UniCAP method), which can detect an activated form of tryptase. We examined the relationship between BALF tryptase levels and clinical parameters of the diseases. BALF tryptase was detected in 7 (18.4%) patients with sarcoidosis, 7 (30.4%) with CVD, and 14 (45.8%) with IPF. In tryptase-positive group, serum ACE levels and the numbers of BALF-mast cells and lymphocytes were higher than the tryptase-negative group in sarcoidosis, serum LDH levels were higher in CVD, and the number of BALF-lymphocyte and Hugh-Jones grade were higher in IPF. Furthermore, tryptase-positive IPF cases had a poorer outcome than the tryptase-negative group by Kaplan-Meier analysis. Tryptase in BALF detected with the UniCAP method may be associated with disease activity in sarcoidosis and CVD, and with severity and poor prognosis in IPF. BALF tryptase measurement may be useful in the assessment of disease activity and severity in various interstitial lung diseases.