Traffic-related air pollutants induce the release of allergen-containing cytoplasmic granules from grass pollen.
OBJECTIVE
Pollen cytoplasmic granules (PCG) are loaded with allergens. They are released from grass pollen grains following contact with water and can form a respirable allergenic aerosol. On the other hand, the traffic-related air pollutants NO2 and O3 are known to be involved in the current increase in the prevalence of allergic diseases via their adjuvant effects. Our objective was to determine the effects of air pollutants on the release of PCG from Phleum pratense (timothy grass) pollen.


METHODS
P. pratense pollen was exposed to several concentrations of NO2 and O3. The induced morphological damages were observed by environmental scanning electron microscopy, and the amount of PCG released from the pollen upon contact with water was measured.


RESULTS
The percentages of damaged grain were 6.4% in air-treated controls, 15% after treatment with the highest NO2 dose (50 ppm) and 13.5% after exposure to 0.5 ppm O3. In treated samples, a fraction of the grains spontaneously released their PCG. Upon subsequent contact with water, the remaining intact grains released more PCG than pollen exposed to air only.


CONCLUSIONS
Traffic-related pollutants can trigger the release of allergen-containing granules from grass pollen, and increase the bioavailability of airborne pollen allergens. This is a new mechanism by which air pollution concurs with the current increase in the prevalence of allergic diseases.
Laboratory of Allergology and Pulmonary Diseases, Department of Pathology and Laboratory Medicine, Groningen University Medical Center, Groningen University, Groningen, The Netherlands. a.motta@path.umcg.nl
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Motta
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Marliere
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Peltre
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Sterenberg
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Lacroix
D000393:Air Pollutants; D000485:Allergens / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000737:chemistry; D006801:Humans; D018986:Motor Vehicles; D031784:Phleum / Q000648:ultrastructure; D011058:Pollen / Q000648:ultrastructure
D000393:Air Pollutants; D000485:Allergens