You're forced to leave as your asthma attack worsens, and soon you're breathing easily. But, six to nine hours later, you start wheezing again. Not necessarily, says Dr. Redwan Moqbel, an international authority on asthma and a member of the Pulmonary Research Group at the University of Alberta. He explains that the allergic response in asthma is complex. Now we know there's a lot more going on.
Eosinophils come out of the bone marrow, enter the blood, and make their way to the airways.
There, they wreak havoc by releasing certain proteins which kill the cells that line the airways. Over time, after prolonged periods of inflammation, eosinophils damage the airway tissue and the thickened airway walls no longer react to medication, such as corticosteroids, which had previously been effective at reducing the airway inflammation. Dr. Moqbel's research team has played an important role in illuminating exactly how eosinophils, whose natural role is to protect us from parasitic worms, can cause damage. Besides releasing proteins which damage cells, eosinophils can also make, store and secrete a number of key mediators of inflammation, called cytokines and chemokines. These regulate the activity of the eosinophils themselves, as well as other cells.