Studies of cytokine levels in bronchoalveolar fluid lavage from patients with interstitial lung diseases.

Cytokine levels in bronchoalveolar lavage fluid from patients with eosinophilic pneumonia (n = 7), allergic alveolitis (n = 11), (cryptogenic) fibrosing alveolitis (n = 8), sarcoidosis (n = 10) were determined, as well as levels in control samples from healthy non-smoking volunteers (n = 11). Fibronectin levels were increased in all the patient categories, the highest absolute levels of fibronectin (100-fold increase) being found in eosinophilic pneumonia and allergic alveolitis. TGF-beta (transforming growth factor-beta) was significantly elevated in allergic alveolitis only. There was a significant difference between allergic alveolitis on the one hand and both sarcoidosis and fibrosing alveolitis on the other. Tumour necrosis factor-alpha (TNF-alpha) was significantly increased in eosinophilic pneumonia and allergic alveolitis; allergic alveolitis and fibrosing alveolitis differed significantly in this respect. Platelet-derived growth factor-BB (PDGF-BB) levels were significantly elevated in allergic alveolitis and fibrosing alveolitis. It was found that the level of PDGF-BB was significantly decreased in the case of sarcoidosis, with no overlapping with allergic alveolitis or fibrosing alveolitis. Interferon-gamma (IFN-gamma) was decreased in all patient categories. A significant difference in extent of the decrease was found between allergic alveolitis and sarcoidosis. The interstitial lung diseases thus differed in the pattern of cytokines expressed, indicating that these cytokines could well be a part of the pathogenic process, and also that the measurement of cytokine levels could be diagnostically useful.