EXPRESSION OF IMMUNOREACTIVE ACTIVIN A PROTEIN IN REMODELING LESIONS ASSOCIATED WITH INTERSTITIAL PULMONARY FIBROSIS

The expression of activin A, one of the transforming growth factor-bet a supergene family, was studied in various pulmonary conditions associ ated with interstitial pulmonary fibrosis (3 cases with diffuse alveol ar damage, 6 cases with idiopathic pulmonary fibrosis, and 1 case with pulmonary fibrosis associated with rheumatoid arthritis) using immuno histochemical techniques on paraffin-embedded sections, Controls consi sted of 10 cases with normal pulmonary parenchyma, and 2 cases with pr imary pulmonary hypertension and 1 case with secondary pulmonary hyper tension were also studied The lung specimens from normal parenchyma we akly expressed immunoreactive activin A on the bronchiolar epithelium. In marked contrast, all of the specimens from cases with diffuse alve olar damage and interstitial pulmonary fibrosis demonstrated strong ex pression of activin A on metaplastic epithelium, hyperplastic smooth m uscle cells, desquamated cells, and alveolar macrophages, Pulmonary ar teries from patients with primary or secondary Pulmonary hypertension showed abundant immunoreactive activin A on smooth muscle cells, These findings suggest a potential role for this growth factor, activin A, in the pathogenesis of pulmonary tissue remodeling associated with int erstitial pulmonary fibrosis.