Type III procollagen N-terminal peptides in experimental pulmonary fibrosis and human respiratory diseases.

In order to detect the fibrotic response in lung-tissue, concentrations of type III procollagen N-terminal peptide (P-III-P) were examined in sera and bronchoalveolar lavage fluids from rabbits with bleomycin-induced pulmonary fibrosis, and in sera from patients with various respiratory diseases, using a radioimmunoassay method. In the bleomycin-induced pulmonary fibrosis, a significant (p less than or equal to 0.05) rise in P-III-P levels was observed in the lavage fluid at 7 days, and in the sera at 21 days after bleomycin treatment, with histological confirmation of pulmonary fibrosis. Many of the patients with pulmonary fibrotic changes had significantly elevated serum P-III-P level. In lung cancer patients, most of the post-radiation serum samples were found to have P-III-P levels greater than or equal to 18 ng/ml. These results suggest that the increase in P-III-P levels is the reflection of fibrotic changes in the lungs and that the clinical assessment of serum P-III-P level could be important in the early detection of pulmonary fibrosis.