Hypereosinophilia

What is hypereosinophila/HES?

Hypereosinophilia or Hypereosinophilic Syndrome (HES) is a blood conditon with high numbers of eosinophils.  Eosinophils are a type of white blood cell involved in the immune system protection against certain infections cause by parasites. The number of eosinophils in the blood can increase due to infection, certain medications, allergic responses, and cancer. In other cases, the increase in eosinophils is due to either an acquired genetic defect in the eosinophils themselves or in associated other immune cells called t-lymphocytes. In these last two cases, the eosinophils may cause additional tissue damage by invading organs such as the skin, lungs, heart, colon, and liver.  When this occurs, we use the term hypereosinophilic syndrome (HES).

Symptoms and Diagnosis of hypereosinophilia

Symptoms of hypereosinophilia are due to the release of substances in the eosinophils that cause tissue damage. Symptoms may include fever, rash, itching, cough, wheezing, shortness of breath, diarrhea, and enlargement of lymph nodes or organs. The diagnosis is made by blood tests including peripheral blood smear and by biopsy of affected organs, and possibly a bone marrow biopsy. Tests are performed to evaluate for secondary causes including stool cultures for parasites. Your doctor may ask you to stop taking certain medication or supplements temporarily. 

Doctors who specialize in allergies may be asked to performe tests for allergans. If secondary causes are not found and an HES is suspected then specific genetic tests may be performed for a mutated protein in the eosinophils called FIP1L1-PDGFR-alpha and other tests performed to look for abnormal t-cells.

Treatment of Eosinophilia/HES

For secondary eosinophilia, treatment is only indicated to relieve symptoms and otherwise should be directed at the underlying cause. Drugs that suppress the action of the eosinophils and lymphocytes are used. For HES, some patients can be managed with steroids alone where as others need stronger immunosuppressants.  If the FIP1L1-PDGFR-alpha mutation is present, the drug imatinib (used for the treatment of CML) is very effective.  The goal of treatment is to relieve symptoms and reduce and prevent damage to organs.  Complete cures are unlikely.