Effects of nitrogen dioxide exposure on bronchoalveolar lavage proteins in humans.

Nitrogen dioxide (NO2) is a pollutant of both outdoor and indoor atmospheres that has the potential to alter alveolar epithelial permeability. In order to assess alterations in the protein content of alveolar lining fluid induced by brief (3-h) exposures to low-level NO2, normal volunteers were exposed sequentially to air and NO2, separated by at least 2 wk, in an environmental chamber. Bronchoalveolar lavage (BAL) was performed after exposure. Four experimental protocols were used: (1) continuous 0.60 ppm NO2 with BAL performed 3.5 h after exposure (n = 8), (2) background 0.05 ppm NO2 with three 15-min peaks of 2.0 ppm followed by BAL 3.5 h after exposure (n = 15), (3) continuous 0.60 ppm NO2 with BAL performed 18 h after exposure (n = 8), and (4) continuous 1.5 ppm NO2 with BAL 3.5 h after exposure (n = 15). No changes in lavage fluid levels of total protein or albumin were observed in response to NO2. However, exposure to continuous 0.60 ppm NO2 was associated with increases in lavage fluid levels of the antiprotease alpha-2-macroglobulin (alpha 2M) when assessed 3.5 h after exposure (air versus NO2: 20 +/- 1 versus 29 +/- 2 ng/ml, P = 0.01). No significant changes in levels of alpha 2M in BAL fluid were observed in the other exposure protocols. Lavaged cell numbers, differential counts, and viability were not altered by exposure to the pollutant.(ABSTRACT TRUNCATED AT 250 WORDS)