Recently, we published an analytical two-dimensional electrophoresis (2-DE) protein map of human bronchoalveolar lavage fluid (BALF) using a pool of BALFs from various patients. In this report, the effect of lung disorders on the protein composition of the lung epithelial lining fluid was investigated by 2-DE of BALFs from individual patients with well-defined interstitial lung diseases: sarcoidosis, idiopathic pulmonary fibrosis (IPF) and hypersensitivity pneumonitis (HP), using improved experimental conditions. On these gels, about 600-1000 stained protein spots could be identified in a BALF sample containing 25 mu g of protein, and our original human BALF protein database has, therefore, been considerably extended. Altogether, 429 protein spots corresponding to 66 different proteins (including isoforms, protein subunits and fragments) were identified by microsequence analysis and by matching with a human blood plasma 2-DE protein map available in the SWISS-2DPAGE database. A human 2-DE BALF database was established and is available on the World Wide Web (http://www.umh.ac.be/similar to biochim/proteomic.htm). The significance of the modifications observed between the different lung pathologies is discussed with the aim of understanding the mechanistic bases of lung disease pathogenesis and finding new potential lung markers of disorders.