• INCLUSION CRITERIA:

Subjects must meet all of the inclusion criteria:

All Subjects must:

1. Be greater than or equal to 18 years of age and less than or equal to 65 years of age.
2. Be willing to have samples collected and stored for future research.
3. 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:

1. 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

2. 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

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

Subjects with Other Allergic and Inflammatory Diseases:

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. Have no history of allergies, asthma or food allergy
2. Have a negative ImmunoCAP fx5 in vitro food allergy screen for allergen specific IgE to egg white, milk, cod, wheat, peanut, and soy
3. 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:

All Subjects must:

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 (see Appendix C)
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 C3. 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.