Immunopathogenesis of Food Allergy and Eosinophilic Gastrointestinal Disorders

Food allergy refers to a number of disorders characterized by clinical diseases associated
with abnormal immune responses to food antigens. Classical IgE mediated anaphylactic food
allergy is characterized by immediate hypersensitivity, and has a prevalence of approximately
6% and 3% in children and adults, respectively. In contrast, eosinophil associated
gastrointestinal disorders (EGIDs), including eosinophilic esophagitis (EoE) and eosinophilic
gastroenteritis (EG), are food allergy associated disorders characterized by eosinophilic
inflammation of the gut, typically without anaphylaxis. Progress in the treatment and
management of these food allergies requires further understanding of the immunological
pathogenesis of these disorders. A subset of peripheral blood food allergen specific
interleukin (IL) -5 producing T cells that are present in EGID but not peanut allergic
subjects has recently been characterized. The primary objective of this study is to determine
if similar IL-5 producing T cells are present in the gut of EGID subjects. To this end, both
EGID and healthy non-allergic subjects will be enrolled and gastrointestinal biopsies will be
obtained for intracellular cytokine staining, RT-PCR and ELISA.

Additionally, this protocol will supply blood and leukapheresis samples for exploratory
studies on immunologic mechanisms underlying anaphylactic food allergy and EGIDs. A total of
up to 400 subjects recruited from outside physician referrals and support groups, as well as
from those in existing National Institutes of Health (NIH) protocols will be enrolled in this
Clinical Center study.

- INCLUSION CRITERIA:

Subjects must meet all of the inclusion criteria:

All Subjects must:

1. Be willing to have samples collected and stored for future research.

2. Have a documented clinical history compatible with EGID, peanut allergy, or other
allergic and inflammatory diseases or be healthy without known allergic conditions.

In addition to the above inclusion criteria for all subjects, the subjects in the following
groups must meet additional group-specific inclusion criteria.

Subjects with EGID must:

1. Be greater than or equal to 18 years of age

2. Maintain a primary non-NIH physician for routine care

3. Have one of the types of EGID below:

- Eosinophilic gastroenteritis: Have a clinical history of eosinophilic
gastroenteritis -including gastrointestinal symptoms-, and histological evidence
of stomach or duodenal eosinophilia with no other known etiology for the
eosinophilia despite careful clinical evaluation.

OR

-Eosinophilic esophagitis: Have a diagnosis of eosinophilic esophagitis, including evidence
of esophageal dysfunction with a peak count of greater than or equal to 25 eosinophils per
high powered field, for which the biopsy was obtained while under proton pump inhibitor
treatment.

OR

-Probable eosinophilic esophagitis: Have a likely diagnosis of eosinophilic esophagitis,
based on evidence of esophageal dysfunction and a peak count of greater than or equal to 15
eosinophils per high powered field, but for which the biopsy was not obtained under proton
pump inhibitors (per section 6.3). To confirm

a diagnosis of EoE, these subjects may be treated with proton pump inhibitor therapy at
recommended doses for gastroesophageal reflux disease for at least 84 weeks prior to EGD
and biopsy. The decision to recommend diagnostic biopsy will be according to concensus
guidelines [7] and current standards of care: based on the severity of symptoms, history of
food impactions, and evidence of remodeling (strictures).

Subjects with Peanut Allergy:

1. Be greater than or equal to 18 years of age and less than or equal to 65 years of age.

2. Have a history of immediate hypersensitivity to peanuts with involvement of at least
one extracutaneous site, including wheezing, laryngeal edema, angioedema, vomiting,
diarrhea, hypotension and circulatory collapse.

3. Have peanut specific IgE of greater than or equal to 5 kIU/L.

Subjects with Other Allergic and Inflammatory Diseases:

1. Be greater than or equal to 18 years of age and less than or equal to 65 years of age.

2. These subjects must be diagnosed with an allergic or an inflammatory disease,
including anaphylaxis, asthma, or hay fever. Diagnosis will be based on established
criteria for each clinical entity.

Healthy, Non-Atopic Subjects:

1. Be greater than or equal to 18 years of age and less than or equal to 65 years of age.

2. Have no history of allergies, asthma or food allergy

3. Have a negative ImmunoCAP fx5 in vitro food allergy screen for allergen specific IgE
to egg white, milk, cod, wheat, peanut, and soy

4. Have a negative Phadiatop allergy screen

EXCLUSION CRITERIA:

Subjects with any of the following criteria will be excluded:

1. Any other condition that, in the investigator s opinion, places the subject at undue
risk by participating in the study

Subjects with Peanut Allergy with any of the following will be excluded:

1. Chronic upper GI symptoms that are consistent with EGID (dysphagia, nausea, vomiting,
abdominal pain/cramps, early satiety)

PROCEDURAL INCLUSIONS:

Subjects with EoE and EG undergoing research EGD or lymphapheresis must:

1. Be greater than or equal to 18 years of age and less than or equal to 65 years of age.

Subjects with EG undergoing EGD or lymphapheresis must have:

1. Histological evidence of stomach or duodenal eosinophilia with a peak count greater
than or equal to 40 eosinophils per high powered field

2. Greater than two positive allergen skin tests or antigen specific IgE tests out of the
following panel (peanut, wheat, soy, shrimp, egg white, milk, walnut, cod, corn)

Subjects with either EG or EoE undergoing lymphapheresis must have:

1. An absolute eosinophil count of >750 eos/microL at least once in the last 2 years

Subjects with EoE undergoing EGD must have:

1. Diagnosed EoE per section 5.1 with a previous biopsy showing greater than or equal to
25 eosinophils per high powered field, OR

2. Probable eosinophilic esophagitis per section 5.1 with a previous biopsy showing
greater than or equal to 25 eosinophils per high powered field

PROCEDURAL EXCLUSIONS:

Subjects with any of following will not undergo EGD:

1. Uncontrolled asthma or Grade 3 or higher by the American Society of Anesthesiologist s
(ASA) Physical Status Classification System.

2. History of adverse reaction to conscious sedation required for EGD.

Subjects with any of following will not undergo EGD or lymphapheresis:

1. Hemoglobin <12 g/dL

2. Viral screens positive for HIV or hepatitis B or C

3. Pregnant or breast-feeding women

Control Subjects (Healthy, Non-Atopic) Undergoing EGD with any of the following will be
excluded:

1. History of reflux or use of acid suppression medication within the last 6 months.

2. Chronic gastrointestinal disease or immunological disease.

3. Clinically indicated EGD in the past 12 months.

4. Use of systemic corticosteroids in the past 6 months.

EGID subjects who are pregnant or breast-feeding may be followed without research
phlebotomy.