Bronchoalveolar lavage: role in the pathogenesis, diagnosis, and management of interstitial lung disease.

Bronchoalveolar lavage has emerged as a useful technique for the study of pulmonary interstitial disorders. Several types of information are provided by the evaluation of lavage fluid. First, the identification of cellular constituents helps to separate inflammatory processes in which lymphocytes predominate (for example, sarcoidosis, hypersensitivity pneumonitis, and berylliosis) from those in which neutrophils or macrophages predominate (for example, idiopathic pulmonary fibrosis and histiocytosis X). Second, the cells removed during lavage can be studied for their immune properties and function; tested with specific antigens, in diseases such as berylliosis and hypersensitivity pneumonitis; and examined for the presence of unique surface antigens with monoclonal antibodies (for example, histiocytosis X). Third, in conjunction with scanning electron microscopy and electron probe analysis, lavage makes possible the identification of inorganic particles in alveolar macrophages of patients with pneumoconiotic lung disease. Finally, although lavage is still an investigative procedure for most pulmonary disorders, it has an established role in the diagnosis of opportunistic infections in the immunocompromised patient.