Food-Specific and Component IgE Threshold Levels That Predict Food Allergy in People With Elevated Total Serum IgE Levels and Atopic Dermatitis

Background: Atopic dermatitis (AD), also called eczema, makes skin dry, red, and itchy. People with AD are more likely to get a food allergy than people without AD. But some food allergy tests are not always accurate in people with AD. Researchers want to study if people are truly allergic to milk and/or peanuts. Objectives: To improve the ways doctors test for food allergy in people with AD. Eligibility: People ages 3-21 who have had AD; have a high total IgE level (an allergic antibody); might have a milk and/or peanut allergy; and are currently enrolled in another NIH study Design: Participants will be screened under another protocol. Participants will have a physical exam, blood tests, and medical history. Participants will breathe into a plastic device that measures lung strength. Participants may get a small plastic tube inserted in their arm. Participants who have not had an allergic reaction to food in the past 3 years will do 1 or more oral food challenge (OFCs) depending on their allergies. They will eat a little bit of the food they might be allergic to. They will be watched for a reaction. If they have one, they will know for sure they are allergic. They may keep eating bigger portions of the food until they either have a reaction or finish all the food. In some OFCs, participants will get a placebo food. OFCs will last a few hours or 2 days. Participants will repeat all tests at each OFC. Participation can last up to 12 months. ...

Allergy skin prick tests and measurement of food-specific immunoglobulin E (IgE) levels are common but not robust means to diagnose food allergy, so patients may be placed on overly restrictive food elimination diets as a result of false-positive results. Such restrictions can lead to poor weight gain, malnutrition, and negative impact on quality of life. More than half of patients who are sensitized (ie, have a positive IgE test) to a particular food do not react to it during an oral food challenge, the gold standard for diagnosing food allergy. Development of food allergy does not always correlate to food-specific IgE levels. The care of these patients would be dramatically improved if decision points for food-specific or component IgEs could be identified that predict when an immediate hypersensitivity is present. This is especially an issue among patients with atopic dermatitis (AD), the most common chronic, relapsing inflammatory disorder of the skin affecting children. Patients with AD are more likely to develop other allergic conditions, including food allergy and sensitization. AD patients are also likely to have high levels of total serum IgE. In this study, participants aged 3-21 years (n = 175) with elevated total serum IgE levels and a history of AD will undergo open feedings and/or double-blind, placebo-controlled food challenges (DBPCFCs). Open feedings will be 1- or 2-step, depending on how often the participant regularly consumes the food at home. There are two DBPCFCs to milk: milk powder or placebo baked into a muffin, and straight milk powder or placebo mixed with a vehicle. The DBPCFC for peanut will be done with peanut flour or placebo mixed with a vehicle. Blood will be collected during the study for measurement of total and component IgEs as well as potential biomarkers of food sensitization vs. immediate hypersensitivity and reaction severity. From these data, we hope to identify diagnostic IgE threshold levels that will inform when oral food challenges are warranted in patients with elevated total serum IgE levels and AD, which is critically needed in the allergy field to facilitate the care of these patients.