Assessment of Glucocorticoid Responsiveness and Mechanisms of Resistance in Hypereosinophilic Syndromes

Detailed Summary

Background: \- Hypereosinophilic syndrome (HES) is a disorder in which the body has too many eosinophils (a type of white blood cell). Too many eosinophils in HES can cause damage to the heart, nerves, or skin. Certain drugs can help lower eosinophil counts to prevent tissue damage. Corticosteroids, such as prednisone, are used for initial therapy in this disorder. Although most people respond to prednisone, some people develop side effects from it, or do not respond very well to treatment. Better ways of determining the dose to give could help to decide on the best therapy for HES. Objectives: * To determine whether a single-dose of prednisone can be used to predict which people with hypereosinophilia respond to treatment. * To study lack of response to steroid treatment in people with HES. Eligibility: Inclusion criteria: * Individuals with hypereosinophilic syndrome with high eosinophil counts. * Individuals who are willing to have blood drawn before and after getting steroids. Exclusion criteria: * Individuals who are on more than 10mg of prednisone (or similar drug) * Individuals with hypereosinophilic syndrome who are on other medications that could interfere with the study * Women who are pregnant or breast-feeding * Individuals who have a known gene mutation associated with chronic eosinophilic leukemia * Children less than 18 years old who weigh less than 48kg or 106lb Design: * Participants will have a screening visit with a physical exam and medical history. Blood and urine samples will be collected. * Participants will have a single dose of the steroid prednisone by mouth in the morning. Blood samples will be collected 2, 4, 24 hours after this dose. * On the day after the steroid dose, participants will provide another blood sample in the morning. * Participants will start to take prednisone daily when they return home. Blood samples will be collected weekly at the participant s doctor s office. The dose of prednisone will be lowered depending on the weekly eosinophil count. We will try to get each person on the lowest dose of prednisone possible that will control the disorder. Participants who do not respond or have severe side effects will be taken off prednisone. Other treatments will be considered for people who do not respond to steroids. The goal is to evaluate the response to prednisone. Our research will try to figure out why some people do not respond to steroids. Most people will complete the study within 6 to 16 weeks, depending on their response to prednisone.

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