Effects of ozone on ovalbumin sensitization in guinea pigs

The effects of ozone on allergen sensitization is still controversial. This study is aimed to clarify the effect of ozone on airway hypersensitivity to ovalbumin (OVA) in guinea pigs, by exposing them to ozone (3 ppm 2 hours daily) and OVA (1 gm/dL 10 min weekly) for two weeks. OVA specific IgG and airway hypersensitivity to methacholine were determined after the sensitization. The results demonstrated that there was a synergistic effect of ozone on OVA-induced IgG antibody production. OVA specific IgG was 0.51 +/- 0.1 U/mL and 0.46 +/- 0.1 U/mL using OVA and ozone alone respectively, which increased to 1.09 +/- 0.4 U/mL when both OVA and ozone were given simultaneously. Ozone exposure was able to cause airway hypersensitivity. The provocation dose of methacholine causing a 100% increase of airway resistance (PD 100 airway resistance) was 0.54 +/- 0.19 mg/mL and 1.17 +/- 0.30 mg/mL using OVA and ozone exposure alone, which had decreased to 0.49 +/- 0.18 mg/mL when both OVA and ozone were given simultaneously. There were macrophages around the peribronchial tissue in all guinea pigs except in the control. The macrophages in the group of OVA with ozone (24.2 +/- 7.2 cells/HPF) were significantly more than those in the OVA group (18.0 +/- 4.2 cells/HPF) and the ozone group (14.5 +/- 6.2 cells/HPF). When OVA-presensitized guinea pigs were exposed to ozone immediately or daily for two weeks, a restrictive type of lung function impairment with similar airway hypersensitivity post ozone exposure was observed. In conclusion, guinea pigs exposed to ozone in conjunction with aeroallergen may not only facilitate the damage of the airway but also enhance antibody production to the aeroallergen. The ozone-induced airway inflammation might have a contributing effect on OVA induced airway hypersensitivity in guinea pigs.