Procollagen III peptide in bronchoalveolar lavage fluid. A potential marker of altered collagen synthesis reflecting pulmonary disease in sarcoidosis.

Type III procollagen N-terminal peptide was not detectable in bronchoalveolar lavage fluid from healthy volunteers but was present in fluid from the majority of patients with pulmonary sarcoidosis (N = 110); the mean concentration was 0.6 micrograms/liter returned fluid, range less than or equal to 0.2 to 19.5 or, expressed in relation to the amount of albumin recovered, 9.5 mg/gm albumin (range less than or equal to 1 to 45). The serum concentrations in the patients with sarcoidosis were normal. Significant inverse correlations were found between lavage fluid procollagen peptide and vital capacity (p less than 0.001), forced expiratory volume (p less than 0.01), and diffusion capacity (p less than 0.01). Lavage fluid procollagen peptide was also related to pulmonary radiological findings (p less than 0.001) and serum levels of angiotensin converting enzyme (p less than 0.001). These findings support the hypothesis that procollagen peptide in lavage fluid is a potential marker of activated pulmonary fibroblasts or an expanded fibroblast mass associated with interstitial lung fibrosis.