Air pollutants boost potency of common airborne allergens

A pair of air pollutants linked to climate change could also be major contributors to the unparallelled rise in the number of people sneezing, sniffling and wheezing during allergy season, scientists have warned.
Researchers found that the gases, nitrogen dioxide and ground-level ozone, appear to provoke chemical changes in certain airborne allergens that could increase their potency.
That, in combination with changes in global climate, could help explain why airborne allergies are becoming more common, researchers said.
"Scientists have long suspected that air pollution and climate change are involved in the increasing prevalence of allergies worldwide. But understanding the underlying chemical processes behind this phenomenon has proven elusive," said Ulrich Poschl, of the Max Planck Institute in Germany.

"Our research is just a starting point, but it does begin to suggest how chemical modifications in allergenic proteins occur and how they may affect allergenicity," Poschl said.
In laboratory tests and computer simulations, researchers studied the effects of various levels of ozone and nitrogen dioxide on the major birch pollen allergen called Bet v 1.

The researchers determined that ozone - the main component of smog - oxidises an amino acid called tyrosine that helps form Bet v 1 proteins.
This transformation sets in motion a chain of chemical reactions that involves reactive oxygen intermediates and can bind proteins together, altering their structures and their potential biological effects.

When this occurs, the cross-linked proteins can become more potent allergens.
Poschl's team also found that nitrogen dioxide, a component of automobile exhaust, appears to alter the polarity and binding capabilities of Bet v 1 allergenic proteins.
This, in conjunction with the effects of ozone, the researchers predict, may enhance the immune response of the body to these particles, particularly in humid, wet and smoggy environments.
The scientists plan to identify other modified allergenic proteins in the environment and hope, in collaboration with biomedical researchers, to study their effects on the human immune system, which may also be affected by other physiological factors.

The research was presented at the 249th National Meeting and Exposition of the American Chemical Society (ACS) in Denver.