Eosinophil Activation and Function in Parasitic Infections and Other Conditions With Increased Tissue or Peripheral Blood Eosinophilia in Humans

  • participants needed
  • sponsor
    National Institute of Allergy and Infectious Diseases (NIAID)
Updated on 23 October 2022
blood tests
heart disease
blood test
toxic substances
blood eosinophil count
genetic testing
local swelling


This study will investigate how, why and under what conditions eosinophils (a type of white blood cell) become activated and will examine their function in immune reactions. Eosinophil counts often rise in response to allergies, asthma, and parasitic worm infections. They can also go up in uncommon autoimmune conditions and, rarely, in association with tumors. Elevated levels of these cells is called eosinophilia. Usually, eosinophilia causes no apparent symptoms, but in rare cases there may be local swelling and itching, allergic lung problems, heart disease or nerve damage caused by the release of toxic substances in these cells into body tissues.

Patients 1 to 100 years of age with eosinophil counts greater than 750/ml or an abnormal accumulation of eosinophils in the skin or body tissues may be eligible for this study. All participants will have a thorough medical history, physical examination and blood tests. Depending on the person's age and symptoms, other diagnostic tests may be done, including specialized studies of the eye, lungs, skin, bone marrow, nerves or heart. This is not a treatment study, and no experimental treatments will be offered. Patients who require treatment will receive standard medical care.

Certain other procedures may be requested solely for research purposes. All participants will be asked to donate extra blood for laboratory studies investigating how immune cells and other immune substances in the blood act to stimulate a rise in eosinophils. In addition, some participants may undergo one or more of the following:

  • Annual Follow-up evaluations - Physical examinations and blood tests to evaluate changes in the patient's condition and eosinophil counts over time.
  • Bone marrow biopsy and aspiration will be recommended during the initial evaluation, and in certain patients at other times when it is important to look directly at the newly developing cells in the bone marrow. For this procedure an area of skin and bone is anesthetized with xylocaine (an anesthetic similar to that used by dentists), and a very sharp needle is used to sample the bone marrow for evaluation. Bone marrow biopsy and aspiration can have side effects of pain and/or bleeding into the skin and soft tissues at the site of the procedure. Rarely the area at the biopsy site can become infected, and is treated with antibiotics.
  • Genetic testing: Some of the blood drawn from you as part of this study will be used for genetic tests. Genetic tests can help researchers study how health or illness is passed on to you by your parents or from you to your children. Any genetic information collected or discovered about you or your family will be confidential.
  • Leukapheresis (only patients 18 years and older) to collect large numbers of certain cells - In this procedure, whole blood is collected through a needle placed in an arm vein. The blood circulates through a machine that separates it into its components. The white cells are then removed and the rest of the blood is returned to the body, either through the same needle used to draw the blood or through a second needle placed in the other arm.


Study Description: This study is designed to collect data and clinical samples from participants with elevated eosinophil counts in the peripheral blood or tissues or their relatives to enhance our understanding of the mechanisms driving eosinophilia and eosinophil activation in patients with a wide range of eosinophilic disorders with the ultimate goal of improving diagnostics and identifying novel treatment modalities for these patients. Eosinophilic participants will undergo an extensive clinical evaluation at baseline and at least yearly thereafter focused on the identification of the cause of eosinophilia and the presence of end organ manifestations. Blood, bone marrow, tissue, and/or body fluids will be collected for research purposes at initial and follow-up visits to address broader questions relating to the varied etiologies of eosinophilia, biomarkers of disease activity and eosinophil activation, and the functional role of eosinophils in homeostasis and disease pathogenesis. While this protocol is not primarily designed to study treatment of eosinophilic patients, the clinical and immunological responses to therapy will be monitored. This protocol will also allow clinical and laboratory evaluation of family members of subjects with eosinophilia to help identify genetic causes of eosinophilia and to provide controls for immunologic studies.

Objectives: Primary Objective: to understand the mechanisms driving eosinophilia and eosinophil activation in patients with a wide range of eosinophilic disorders

Secondary Objectives:

  1. To develop a diagnostic algorithm that accurately classifies eosinophilic patients by underlying etiology
  2. To determine the mechanisms underlying eosinophil activation and recruitment to the blood and tissues
  3. To understand the mechanisms of action of therapeutic agents used or in development for the treatment of HES
  4. To assess the signs and symptoms experienced by patients with HES

Exploratory Objectives:

  1. To investigate the multifunctional role of eosinophils in settings other than HES
  2. To understand the long-term effects of eosinophilia in patients with HES

Primary Endpoint:

Identification and characterization of clinical and genetic variants of hypereosinophilic syndromes (HES)

Secondary Endpoints:

  1. Identification of laboratory and clinical tests that distinguish between clinical and genetic variants of HES

2a. Identification of biomarkers of disease activity and specific organ involvement in eosinophilic disorders

2b. Identification of new therapeutic targets for the treatment of HES

3. Delineation of the effects of therapeutic agents on eosinophil development, activation, recruitment to tissues and/or apoptosis

4. Creation of a patient-related outcomes questionnaire for use in future treatment studies of HES

Exploratory Endpoints:

  1. Description of the consequences of eosinophilia and/or eosinophil depletion in the context of varied immunologic and inflammatory


2. Collection of standardized longitudinal data on disease activity and outcome in patients with hypereosinophilia.

Condition Immune System Diseases, Eosinophilia, Helminthiasis, Hypersensitivity, Parasitic Disease
Clinical Study IdentifierNCT00001406
SponsorNational Institute of Allergy and Infectious Diseases (NIAID)
Last Modified on23 October 2022


Yes No Not Sure

Inclusion Criteria

In order to be eligible to participate in this study, an individual must meet all of the
following criteria
Stated willingness to comply with all study procedures and availability for the
duration of the study
Male or female, aged 1-100
Ability of subject (or Legally Authorized Representative (LAR)) to understand and sign
a written informed consent document
Eosinophilic Patients only
Documented peripheral blood count >1500/mm3, tissue eosinophilia (abnormal
accumulation of eosinophils in the skin or other body tissues) or suspected
eosinophilic end organ involvement
Primary (non-NIH) physician for routine medical care
Relatives only
Extended family member of an eosinophilic participant on this protocol

Exclusion Criteria

An individual who meets any of the following criteria will be excluded from participation
in this study
Any condition(s) or diagnosis, physical and/or psychological, that the investigator
feels precludes the patient from participation in the study
Relatives only
Females must not be pregnant
Clear my responses

How to participate?

Step 1 Connect with a study center
What happens next?
  • You can expect the study team to contact you via email or phone in the next few days.
  • Sign up as volunteer  to help accelerate the development of new treatments and to get notified about similar trials.

You are contacting

Investigator Avatar

Primary Contact


Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

Learn more

If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

Learn more

Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

Learn more

Similar trials to consider


Browse trials for

Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 



Reply by • Private

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note