Repeated Ozone Exposure Induces Th2 Immune Responses in Mice

ABSTRACT

BACKGROUND AND OBJECTIVES: It has been reported that ozone exposure exacerbate allergic rhinitis symptoms and may contribute to increase allergic rhinitis prevalence. However, a causal relationship still remained unsolved. The purpose of this study is to investigate whether prolonged exposure to ozone induce Th2 immune response without allergen. MATERIALS AND METHODS: Fourteen BALB/c mice were divided into two groups control group and ozone exposure group. Mice were exposed to 0.3 ppm of ozone for 4 hours a day, 3 times per week, for 4 weeks. At 24 hour after the last ozone exposure, nasal lavage fluid (NLF) was obtained to measure the levels of cytokine IL-4, IL-5, and IFN-gamma. After lavage fluid was obtained, blood was obtained via inferior vena cava to measure the amount of total IgE and IgG1. The concentration of cytokines and immunoglobulins was measured using the ELISA method. In addition, Luna staining was performed to identify eosinophils infiltrated in nasal mucosa. RESULTS: The levels of IL-4 and IL-5 in NLF were significantly increased in ozone exposure group compared with control group. But the level of IFN-gamma in NLF shows no significant difference between two groups. Serum total IgE and IgG1 were significantly increased in ozone exposure group compared with control group. On histologic examination, number of eosinophils infiltrating nasal mucosa was significantly increased in ozone exposure group. CONCLUSION: These results suggest that repeated ozone exposure induces Th2 response in the nasal mucosa of mice.