Immunologic response in vaccinated mice during long-term exposure to nitrogen dioxide.

Swiss albino mice were continuously exposed to either 2 ppm NO₂, 0.5 ppm NO₂ with daily 1-hour peaks of 2 ppm NO₂, 5 days a week, or to filtered air. After a 12-week exposure the mice were vaccinated with A₂/Taiwan influenza virus vaccine and the exposures to the various environmental conditions continued for an additional 28 weeks. At 2 weeks after vaccination, the serum neutralizing (SN) antibody titers and SN seroconversion rates were depressed to a various extent in mice exposed to NO₂. At 4 weeks after the vaccination and later, the SN antibody titers did not differ significantly among the various groups.Nonvaccinated mice exposed to NO₂ for 12 weeks showed a marked decrease in concentrations (mg/ml) of serum IgA, and an increase in serum IgM, IgG₁ and IgG₂ immunoglobulins. When concentrations of immunoglobulins were adjusted for age of mice after vaccination, a significant elevation was observed in serum IgM, IgG₁ and IgG₂ of mice exposed to NO₂ as compared to controls. During the 2-week period immediately following the vaccination, exposure to NO₂ appeared to be the predominant factor influencing the percentage concentration of the four serum immunoglobulins.