Use of bronchoalveolar lavage to detect lung damage.

The assay of bronchoalveolar washings from acutely exposed animals has proven useful as a rapid screen for lung injury from inhaled airborne toxins. The screen is useful for choosing appropriate compounds and exposure levels for subsequent in-depth studies in which complete histopathologic evaluations will be made. An inflammatory response can be detected by the appearance of polymorphonuclear leukocytes and an increase in protein content of lung washings. The release of the cytoplasmic enzyme, lactate dehydrogenase, into the acellular portion of the lavage fluid serves as an indication of cell death or membrane damage. A large increase in some lysosomal enzymes has been found in the bronchoalveolar lavage fluids from animals chronically exposed to insoluble particles. Angiotensin-converting enzyme has been found to be elevated in bronchoalveolar washings from animals with endothelial cell damage in the pulmonary capillaries. The correlation of these cellular and biochemical alterations in the bronchoalveolar lavage fluid with morphological indications of damage has served to validate this method of detecting acute lung injury. Further study is needed to validate indicators of developing chronic disease.