Modifications of Phleum pratense Grass Pollen Allergens following Artificial Exposure to Gaseous Air Pollutants (O₃, NO₂, SO₂)

Background: Air pollution is frequently proposed as a potential cause of the increased incidence of allergy in industrialised countries. Our objective was to investigate the impact of the major gaseous air pollutants on grass pollen allergens. Methods: Timothy grass pollen was exposed to ozone (O₃), nitrogen dioxide (NO₂) and sulphur dioxide (SO₂) alone or in combination. Allergen contents were analysed by 2-dimensional immunoblot using grass pollen-sensitive patient sera. Results: For O₃-treated pollen, immunoblotting showed an acidification of allergens Phl p 1b, Phl p 4, Phl p 5 and Phl p 6 and an IgE recognition decrease in Phl p 1, Phl p 2, Phl p 6 and Phl p 13. NO₂ exposure induced a decrease in Phl p 2, Phl p 5b and Phl p 6 recognition, and SO₂ treatment induced a decrease in Phl p 2, Phl p 6 and Phl p 13 recognition. Moreover, samples treated with a mix of NO₂/O₃ or NO₂/SO₂ showed a higher decrease in allergen content, compared with samples treated with only one pollutant. The O₃ acidification was also observed with the NO₂/O₃ mix. Conclusion: Exposure of pollen to gaseous pollutants induced a decrease in allergen detection in pollen extracts. This decrease could be due to a mechanical loss of allergens from the altered pollen grains and/or post-translational modifications affecting allergen recognition by IgE.