Determination of various cytokines and type III procollagen aminopeptide levels in bronchoalveolar lavage fluid of the patients with pulmonary fibrosis: inverse correlation between type III procollagen aminopeptide and interferon-gamma in progressive patients.

We measured levels of cytokines and type III procollagen aminopeptides (procollagen III peptides) in bronchoalveolar lavage fluid obtained from 20 patients with stable pulmonary fibrosis (PF) and seven patients with progressive PF, and nine control subjects to determine the role of cytokines in the development of PF. Procollagen III peptide levels were markedly increased in progressive PF patients. Tumour necrosis factor-alpha, interleukin-6, transforming growth factor-beta and interferon-gamma (IFN-gamma) levels were elevated in both PF patients as compared with controls, with a tendency of higher levels in progressive patients, whereas interleukin-1 beta (IL-1 beta) level was decreased in both PF patients. When the correlation between procollagen III peptide and various cytokine levels was analysed the only significant correlation was inversely between procollagen III peptide and IFN-gamma in progressive PF patients. These results indicated that although multiple cytokines may be involved in the development of PF, the negative role of IFN-gamma in active collagen synthesis could be also important.