Eosinophils play two roles in your immune system:

  • Destroying foreign substances. Eosinophils can consume foreign substances — particularly substances related to infection with a parasite — that have been "flagged" for destruction by other components of your immune system.
  • Regulating inflammation. Eosinophils help promote inflammation, which plays a beneficial role in isolating and controlling a disease site. But, sometimes inflammation may be greater than is necessary, which can lead to troublesome symptoms or even tissue damage. For example, eosinophils play a key role in the symptoms of asthma and allergies, such as hay fever. Other immune system disorders also can contribute to ongoing (chronic) inflammation.

Eosinophilia occurs when either a large number of eosinophils are recruited to a specific site in your body or bone marrow produces too many eosinophils. This can be caused by a variety of conditions, diseases and factors, including:

  1. Parasitic and fungal diseases
  2. Allergies, including to medications or food
  3. Adrenal conditions
  4. Skin disorders
  5. Toxins
  6. Autoimmune diseases
  7. Endocrine disorders
  8. Tumors

Specific diseases and conditions that can result in blood or tissue eosinophilia include:

  1. Ascariasis (a roundworm infection)
  2. Asthma
  3. Atopic dermatitis (eczema)
  4. Chronic myelogenous leukemia
  5. Churg-Strauss syndrome
  6. Crohn's disease
  7. Drug allergy
  8. Eosinophilic leukemia
  9. Hay fever
  10. Hodgkin's lymphoma (Hodgkin's disease)
  11. Idiopathic hypereosinophilic syndrome (HES), an extremely high eosinophil count of unknown origin
  12. Lupus
  13. Lymphatic filariasis (a parasitic infection)
  14. Other cancers
  15. Other parasitic infections
  16. Ovarian cancer
  17. Primary immunodeficiency
  18. Trichinosis (a roundworm infection)
  19. Ulcerative colitis

Parasitic diseases and allergic reactions to medication are among the more common causes of eosinophilia. Hypereosinophilic syndrome tends to have an unknown cause or results from certain types of cancer, such as bone marrow or lymph node cancer.

Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.

Apr. 08, 2014