LUNG ALKALINE-PHOSPHATASE AS A MARKER OF FIBROSIS IN CHRONIC INTERSTITIAL DISORDERS

Alkaline phosphatase (ALP) in lung lavage fluids is a marker of tissue damage and type II cell proliferation. Type II pneumocytes are extens ively involved in fibrosis. The aim of our study was to verify whether local ALP activity can be held as a marker of fibrosis in chronic int erstitial lung disorders. ALP was determined in the bronchoalveolar la vage of 140 subjects: 25 control subjects, and 33 patients with silico sis, 38 with idiopathic pulmonary fibrosis (IPF), and 18 with Stage I, 16 with Stage II and 10 with Stage III/IV sarcoidosis. We observed a significant augmentation of ALP activity in patients with IPF, as well as in those with Stages II and III/IV sarcoidosis. Albumin was higher in those with Stages I and II sarcoidosis, but it was normal in the o ther groups. Therefore, a significant increase in ALP:albumin ratio ch aracterized IPF (median, 10.3; range, 2.4 to 83.2) and Stage III/IV sa rcoidosis, (8.9, 4.4 to 103.1) as compared with Stage I (2, 1.1 to 18) and Stage II (4.7, 0.7 to 26.6) sarcoidosis, silicosis (6.5, 0.5 to 4 2.7), and the nonsmoker (6.1, 2.9 to 12.9) and smoker (6.4, 2 to 15.2) control groups. We conclude that an increase of the ALP: albumin rati o in bronchoalveolar lavage fluids from patients with chronic intersti tial disorders may reflect a fibrosing progression.