CD23: Protein Explaining the Food Allergy Mechanism

Filed in archive Diagnostics , Studies on July 30, 2006

According to a study published in the July issue of Gastroenterology (the journal for the members of the American Gastroenterological Association), researchers have identified one of the proteins that may be responsible for causing food allergies. This finding could then lead to the development of more accurate non-invasive tests to identify true food allergies.

Immunoglobulin (antibody) E is a protein produced by plasma cells (or B-Cells, a type of lymphocyte), designed to control the immune response in extracellular fluids by binding to substances in the body that are recognized as foreign.

Since not all patients (especially those with delayed allergies) have detectable levels of immunoglobulin E (IgE) in their serum, testing for food allergy often pose a problem. Even if there are reliable testing methods existing for food and other allergies, like skin tests and serum IgE tests, these may not accurately diagnose food allergies. The most accurate test for food allergy, the oral food challenge is expensive and should be administered under a controlled environment.

The new study, conducted at the Mount Sinai School of Medicine (New York) showed for the first time that a protein normally expressed in a person's intestinal tract called CD23, acts as a receptor for IgE, and enables it to participate in food-allergic reactions.

The study revealed that CD23 was detectable in stool samples from food allergic patients (not in the controls) suggesting either increased levels of CD23 on intestinal cells or an allergen-induced shedding of CD23 in food allergic patients.

A strong correlation between the level of CD23 and food-specific IgE in the stool was established by the researchers which were demonstrated by the availability of IgE antibodies to interact with CD23 on the outside surface of the gastrointestinal wall.

"We believe that the presence of CD23 may provide a surrogate method of looking at the gut without invasive tests like biopsies," according to M. Cecilia Berin, PhD, assistant professor, pediatrics/allergy and immunology, Mount Sinai and lead author of the study"

Based on the results of our study, we intend to conduct larger scale trials of patients with food allergic disorder to determine how CD23 in the stool correlates with clinical findings," according to Dr. Berin. "We hope to determine that CD23 offers a promising target for food allergies that leads to more accurate, easier to tolerate tests for these patients."

Affecting an estimated 6-8% of American children age four years or younger and approximately 2% of adults, food allergies are commonly caused by peanuts, tree nuts, shellfish, fish, wheat, milk, eggs and soy and 3.5-4% of which are IgE-mediated.

Source: EurekAlert