Eosinophils are a type of white blood cell. They help fight off infections and play a role in your body's immune response. They can also build up and cause inflammation.

Normally your blood doesn't have a large number of eosinophils. Your body may produce more of them in response to

• Allergic disorders
• Skin conditions
• Parasitic and fungal infections
• Autoimmune diseases
• Some cancers
• Bone marrow disorders

In some conditions, the eosinophils can move outside the bloodstream and build up in organs and tissues. Treatment of the problem depends on the cause.