INTERACTION OF OZONE AND ALLERGEN CHALLENGES ON BRONCHIAL RESPONSIVENESS AND INFLAMMATION IN SENSITIZED GUINEA-PIGS

Background: Environmental pollutants such as ozone may interact with a irway responses to allergen in sensitised individuals. Methods: We exa mined the effects of a single exposure to ozone (1 ppm for 1 h) on bro nchial 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 pet-formed and protein content and differential cell counts were determined. Results: Ozone increase d 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 in creased at 3 and 24 h after exposure to ozone alone, but there were no further increases with ozone followed by OA exposure. Protein concent ration 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 5 4.0+/-18.1 mg/ml in the control group (p < 0.02 and p < 0.01, respecti vely). Conclusion: Our data demonstrate an interaction of OA with ozon e exposure on bronchial responsiveness; one underlying mechanism could be through damage at the endothelial-epithelial barrier.