Tracing pollution links to asthma, allergy
Bad air tied to disabled immune-regulating cells
By Nathan Seppa
SAN ANTONIO — Bad actors in air pollution may contribute to asthma and allergy by subverting protective cells in the body that tone down immune reactions, researchers report. The pollution components also seem to rev up overactive immune warriors — already linked to allergies — that need no such prompting.
The airborne culprits are polycyclic aromatic hydrocarbons, or PAHs, the products of incomplete burning of fuel in diesel engines, furnaces, wood fires, wildfires and even barbeque grills. Air pollution has been tied to asthma and allergy in past research, but the link between PAHs and these immune problems is still unclear.
In the new report, researchers show that children exposed to high levels of PAHs had poorly functioning T-regulatory cells, or T-regs, which normally ratchet down immune-caused inflammation as needed. “T-regs are peacekeeper cells,” says Kari Nadeau, a physician and biochemist at Stanford University, who presented the findings February 23 at a meeting of the American Academy of Allergy, Asthma and Immunology. “But in asthma, T-regs are impaired.”
The team also found that kids exposed to a lot of PAHs made excess amounts of an antibody called immunoglobulin E, or IgE. The IgE antibody normally helps the body fight parasites. But in developed countries, where parasitic infections are largely a thing of the past, IgE has become better known for its role in allergy. The body often cranks out IgE as part of a misguided immune reaction against noninfectious substances in the environment. IgE also shows up in asthma, which can be triggered by allergy.