Study to Identify Non-Invasive Markers of Gastrointestinal Allergy

The incidence of gastrointestinal allergy is on the rise and can be manifest in a number of different clinical presentations. The goal of this study is to evaluate the measurement of CD23, a protein that can be identified stool, urine, and blood, as a non-invasive marker for use in the diagnosis and interval assessment of patients with known or suspected gastrointerstianl allergy.

Eosinophilic esophagitis (EE) is a disorder typically found in school-age and adolescent children, and is more prevalent in male patients. Patients with EE typically present with symptoms of heartburn or difficulties swallowing. Blood and x-ray studies may be normal or display non-specific findings. The diagnosis of EE rests on a combination of clinical symptoms, and the results of endoscopic and histologic studies. There is currently no biochemical marker that can be used to monitor disease course in these patients.

Cow milk protein intolerance (CMPI) is an allergic process affecting the distal gastrointestinal tract in infants. As such, it often presents as diarrhea without or without the presence of gross rectal bleeding in infants ranging in age from birth to 6 months of age. Children display symptoms of abdominal disress including emesis, cramping, colic, or feeding difficulties. The diagnosis is based on an appropriate clinical history and supporting physical exam (typically normal). Treatment involves removal of the offending dietary antigens which include cow or soy milk protein Eosinophilic crypt abscesses, or collections of eosinophils within the intestine can also be seen.

CD23 is a protein that can be found on allergy-type white blood cells (eosinophils), as well as on the cells that line the gastrointestinal tract. Previous studies have reported increased levels of CD23 in infants with cow's milk allergy. CD23 is also elevated in infants and children with allergic disease. Levels of CD23 appears to fall in conjunction with therapy.