Research Projects

Project at a Glance

Project Status: complete

Title: Health effects from the inhalation of oxidant air pollutants as related to the immune system

Principal Investigator / Author(s): Osebold, John

Contractor: Department of Veterinary Microbiology and Immunology, UC Davis

Contract Number: A7-179-30 A8-122-31 A9-145-31


Research Program Area: Health & Exposure

Topic Areas: Health Effects of Air Pollution


Abstract:

The original proposal, for the studies reported here, was to:

a. Investigate the effects of ozone and sulfuric acid aerosol for enhancing the syndrome of extrinsic asthma.

b. Examine the effects of ozone on altering the severity and pathogenesis of influenza. Mice were chosen as the experimental animal for several reasons. Immunological mechanisms have been more thoroughly studied in mice than in any other species, and much that is known about immune responses in man has come from knowledge obtained as a result of mouse studies. Work was performed in the anticipation of finding distinct links between air pollution and lung diseases. It was intended that data from the studies might contribute toward decision making on pollution levels that are compatible with normal lung function.

Major findings of these studies are:

1. Ozone exposure increases the incidence of allergic lung sensitization to an inhaled allergen. Five extensive experiments were performed. An aerosolized allergen (ovalbumin) was used to mimic the inhalation of environmental allergens such as plant pollen. Significantly greater numbers of animals were allergic in experimental groups where ozone exposure ranged from the high of 0.64 ppm to a low of 0.16 ppm.

2. Sulfuric acid aerosol (concentration of 0.5 and 1.0 mg/m3) did not have a significant effect for the enhancement of allergy to an inhaled allergen. Three experiments were performed. Animals exposed to sulfate alone were not sensitized to a greater extent than the mice breathing filtered ambient air. It was concluded that the allergic enhancement seen in the combined ozone and sulfate groups could be explained on the basis of the ozone effect. This negative finding with respect to sulfuric acid aerosol further delineated the uniqueness of effects on lung tissue from ozone inhalation.

3. In asthma, antibodies of the IgE class are specifically responsible for the disease. Cells producing IgE are distributed along the respiratory mucous membranes and also in the gas exchange tissue. It was important to correlate the allergic state in living animals with cellular responses to show that synthesis of IgE antibody had been stimulated from contact with the allergen. Combined data from three experiments have shown the correct correlation of cells with the sensitivity levels in the animals.

4. Fatal influenza infections were less frequent in ozone exposed animals (0.4 and 0.64 ppm) than in mice breathing ambient air. This observation 'was made in four separate experiments. Two factors appear to interplay in producing this interesting effect.

5. Abnormal respiratory membranes develop as a result of 15 days of continuous ozone exposure, and this appeared to change the role of lining epithelium as host cells for influenza virus.


 

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