Immunologic Basis of Food Protein-Induced Enterocolitis Syndrome

Inclusion Criteria: * Provision of appropriate consent and/or assent * Age 1-60 years * Suspected or confirmed FPIES diagnosis * Reported convincing FPIES reaction (per criteria in 2017 FPIES guidelines) within: (Children \<18 years of age: The past 6-36 months) (Adults age \>18 years: The past 6 months-10 years) * Individuals of childbearing potential practicing sexual abstinence or using effective methods of contraception during study participation * English-speaking Exclusion Criteria: * Past severe FPIES defined as hospitalization due to an acute FPIES reaction with neurological compromise or requiring life support * Acute FPIES reaction in the past 6 months * Frequent gastrointestinal symptoms: nausea, abdominal pain, reflux, heartburn, emesis, diarrhea, constipation per participant or guardian report or as evidenced by FPIES Symptoms Score (FPIES-SS) * Current active eosinophilic gastrointestinal disorders, inflammatory bowel disease, gastroesophageal reflux disease, or any other chronic gastrointestinal condition * Poorly controlled atopic dermatitis at screening per PI discretion * Poorly controlled or severe asthma/wheezing at screening, defined by at least one of the following criteria: 1: History of two or more systemic corticosteroid courses within six months of screening or one course of systemic corticosteroids within three months of screening to treat asthma/wheezing; 2: Prior intubation/mechanical ventilation for asthma/wheezing; 3: One hospitalization or E…