Effects of exposure to NO2 or SO2 on bronchopulmonary reaction induced by Candida albicans in guinea pigs.

The effects of NO2 or SO2 on the bronchopulmonary reactions induced by Candida albicans in guinea pigs were evaluated. Thirty-six guinea pigs (3 groups of 12 animals each) were sensitized with intraperitoneal injection of 10 mg of C. albicans, given twice. Two groups of animals were exposed to about 5 ppm of NO2 or SO2 for 4 h/d, 5 d/wk; this exposure was conducted a total of 30 times during the study. The third group served as the control and was not exposed to these pollutants. Two weeks after the second sensitization, all the animals were subjected to inhalation exposure to C. albicans. For 42 h after the antigen challenge, the respiratory rates and expiration/inspiration ratios of the animals were automatically monitored. The number of animals showing tachypnea was significantly higher in the NO2 exposure group than in the control from 15 h after antigen challenge. In the SO2 exposure group, the number of animals showing prolonged expiration or prolonged inspiration, or both, was significantly higher than that in the control group, and the symptoms were observed from approximately 15 h after antigen challenge. These findings showed that delayed-type dyspneic symptoms in guinea pigs were increased by exposure to NO2 or SO2, although the symptoms and degree of dyspnea were different for the two gases.