This type of asthma is caused by an influx of eosinophil blood cells. While the exact cause is unknown, eosinophils can contribute to airway inflammation and constriction seen in traditional forms of asthma. Eosinophilic asthma may pose more severe symptoms than mild forms of asthma.

What role do eosinophils play in asthma?

During asthma attack, eosinophils are stimulated to release proteins from granules including major basic protein, eosinophil peroxidase, eosinophil cationic protein, and eosinophil-derived neurotoxin, all of which are toxic to the epithelial cells of airway.

What level of eosinophils indicate asthma?

Generally, a sputum eosinophil count of 3 percent or more in a person with severe asthma who experiences persistent flares and symptoms despite using inhalers, would indicate eosinophilic asthma, says Chupp.