Inflammatory molecules released by pollen trigger allergies

How do pollen particles provoke allergic reactions? A new study in the February 21 issue of The Journal of Experimental Medicine puts some of the blame on bioactive molecules that are released from pollen. These molecules bind to immune cells and cause them to launch a typical allergy-promoting immune response. Pollen from plants exposed to air pollutants produce more of these allergy-provoking compounds than do pollen from unpolluted areas, possibly explaining why allergies are more prevalent in places with high levels of car exhaust emissions.

Traidl-Hoffmann and colleagues showed that extracts from birch pollen and other common allergens block the production of a soluble protein by immune cells that normally inhibits allergic reactions. They went on to identify the compound in the pollen extracts that caused the inhibitory response and showed that it was similar to certain pro-inflammatory molecules produced in the body in response to injury or infection. The authors now plan to assess whether cells from allergy-prone people are more sensitive to the effects of the pollen-derived compound than those from non-allergic individuals. A better understanding of these molecules and how they work may eventually lead to new approaches to treating allergies.