Interaction of ozone and allergen challenges on bronchial responsiveness and inflammation in sensitised guinea pigs

Environmental pollutants such as ozone may interact with airway responses to allergen in sensitised individuals.

We examined the effects of a single exposure to ozone (1 ppm for 1 h) on bronchial responsiveness to acetylcholine (ACh) aerosol 3 and 24 h after single ovalbumin (OA) challenge in OA-sensitised anaesthetised guinea pigs. Broncho-alveolar lavage (BAL) was performed and protein content and differential cell counts were determined.

Ozone increased bronchial responsiveness at 3 h but not at 24 h, while OA alone had no effect. At 3 h after ozone, OA induced further, but non-significant increases in bronchial responsiveness to ACh, but at 24 h after ozone, there was enhanced responsiveness. Neutrophil counts in BAL fluid increased at 3 and 24 h after exposure to ozone alone, but there were no further increases with ozone followed by OA exposure. Protein concentration was significantly increased in the ozone and OA groups at 3 and 24 h (163.4 +/- 25.6 and 128.7 +/- 7.4 mg/ml, respectively) compared to 54.0 +/- 18.1 mg/ml in the control group (p < 0.02 and p < 0.01, respectively).

Our data demonstrate an interaction of OA with ozone exposure on bronchial responsiveness; one underlying mechanism could be through damage at the endothelial-epithelial barrier.