Effects of intermittent inhalation exposures to mixed atmospheres of NO2 and H2SO4 on rabbit alveolar macrophages.

Rabbits were exposed (2h/d) to atmospheres consisting of 0.5 mg/m3 (0.3 micron) H2SO4 plus NO2 at either 0.3 (low) or 1 ppm (high). Animals were sacrificed 24 h after 2, 6, or 13 exposures, and cells were recovered from the lungs by bronchopulmonary lavage. Exposure to high NO2 with acid resulted in an increase in neutrophils at all time points and an increase in phagocytic capacity of macrophages after two or six exposures. On the other hand, exposure to the low NO2 with acid resulted in depressed phagocytic capacity and mobility. The results were compared with those for NO2 or H2SO4 given alone.