Effects of Repeated Ozone Exposure on Allergic Responses in Mice

Jin, Yong De; Sung, Yeol Woong; Park, Young Kyu; Kim, Yong Min; Kim, Dong Hyun; Park, Seok Won; Rha, Ki Sang

Abstract

BACKGROUND AND OBJECTIVES: We Investigated whether repeated ozone exposure has a priming effect on allergic sensitization and whether ozone exposure has an exacerbating effect on allergic responses during allergen challenge in previously sensitized animal.
SUBJECTS AND METHOD
Thirty-five female BALB/c mice were divided into the following five groups; controls (I), ovalbumin (OVA)-aerosol exposure group (II), OVA-aerosol/ozone exposure group (III), OVA-systemic sensitization group (IV), and OVA-systemic sensitization/ozone exposure group (V). Mice of group III and V were exposed to 0.3 ppm ozone for 4 hours, three times a week for four weeks. Mice of group II and III were exposed to OVA-aerosol for 20 minutes, five times a week for four weeks. Mice of group IV and V were sensitized by intraperitoneal injections with OVA/Al(OH)3 solution on day 0, 7, and 14. Animals received five consecutive allergen challenges by OVA-aerosol nebulization from day 23 to 27. At 24 hours after the last exposure, nasal lavage fluid (NLF) and blood were obtained. The concentrations of total serum IgE, anti-OVA IgE, and anti-OVA IgG1 were measured by enzyme-linked immunosorbent assay (ELISA). The levels of IL-4, IL-5 and INF-gamma in NLF were measured by ELISA. In addition, Luna staining was performed to identify eosinophils that infiltrated in nasal mucosa.
RESULTS
OVA-aerosol exposure alone induced weak allergic response to OVA in nonsensitized mice. In contrast, the combination of OVA-aerosol and ozone resulted in augmented immune responses to OVA as indicated by significant increases in total serum IgE, anti-OVA IgE, and anti-OVA IgG1 antibody titers, as well as significant increases in the levels of Th2 cytokines In NLF and the number of eosinophils infiltrating nasal mucosa. Although the titers of total IgE and anti-OVA IgE of group III were significantly lower than those of group IV, the titers of anti-OVA IgG1, levels of IL-4 and IL-5, and the number of eosinophIls infiltrating nasal mucosa showed no significant differences between group III and group IV. In sensitized mice, ozone exposure durIng OVA challenge enhanced the allergic responses to OVA.
CONCLUSION
These results suggest that ozone exposure induces and enhances the allergic responses by augmenting the production of allergen-specific antibody and Th2 cytokines.