Recently, scientists at Helmholtz Zentrum in Munich have discovered that pollen of the common ragweed has higher concentrations of allergen when exposed to NO2 exhaust gases. The study also indicates the presence of a possible new allergen in the plant. Researchers of the Institute of Biochemical Plant Pathology (BIOP) studied how nitrogen oxides affect the pollen of the plant, specifically by fumigating the plants with various concentrations of NO2, which is generated during combustion processes of fuel.
The data from the study revealed that the stress on the plant caused by NO2 modulated the protein composition of the pollen, with different isoforms of the known allergen Amb a 1 being significantly elevated. In addition, scientists observed that the pollen from NO2-treated plants have a significantly increased binding capacity to specific IgE antibodies of individuals who are allergic to ragweed, which frequently starts an allergic reaction in humans. The plant researchers also identified a protein, not previously known to be an allergen in ragweed, that was present when NO2 levels were elevated. It has a strong similarity with a protein form a rubber tree, in which context it was previously described as an allergen whose effect was also seen in fungi and other plants.
Due to air pollution, it is expected that the already aggressive ragweed pollen will become even more allergenic in the future. Originating in the Americas, ragweed is believed to have come to Europe through imported birdseed, and due to climate change, it’s become widely dispersed across the continent. Ragweed pollen is very aggressive, and since it doesn’t bloom until late summer, it lengthens the “season” for those who are allergic to it. Studies have already shown that ragweed plants growing along highways are clearly more allergenic than those growing away from road traffic. The researchers plan on doing further studies in the future, where they plan on showing that pollen only treated with NO2 can also elicit stronger in vivo reactions.