The purpose of this study is to observe the natural course of food allergy, including both the development of peanut allergy in infants at high risk for developing this allergy, and the resolution of both egg and cow's milk allergy.

This observational study will investigate the developmental immunology of peanut, egg, and milk allergy in a cohort of milk- or egg-allergic children who are at risk for peanut allergy. This strategy will help to delineate, compare, and contrast biological markers and immunologic changes associated with the development of peanut allergy and loss of egg and milk allergy, while simultaneously evaluating important clinical and environmental influences likely to account for the recent rise in the prevalence of these allergies. The hallmark of food-allergic disease is the production of food-specific Immunoglobulin E (IgE) antibodies that represent an end result of a T helper 2 (Th2) influenced immune response. Currently, there is only a limited understanding of the mechanisms involved in the developmental course of food allergies. To effectively prevent or reverse the progression of food allergy, immune interventions will be needed. Furthermore, it is likely that successful strategies will need to be directed to those persons at identifiable risk (e.g., who have biomarkers associated with development of peanut allergy).

Inclusion Criteria for Children with Food Allergy: Participants who meet all of the following criteria are eligible for enrollment as study participants:

• Atopic dermatitis evaluation

• Either

  1. A convincing clinical history of cow's milk (and/or egg) allergy and a positive prick skin test (≥ 3mm larger than the negative control) to cow's milk (and/or egg, if egg allergy history), or
  2. Moderate to severe atopic dermatitis at the time of enrollment (or by a history prior to removal of milk and/or egg from the maternal (if breastfed) or infant diet) and a positive prick skin test to milk or egg, or
  3. Positive oral food challenge, prior to study entry, to either milk or egg with positive skin test

• Written informed consent from parent/guardian

• Willing to submit specimen for central laboratory plasma peanut IgE

Exclusion Criteria for Children with Food Allergy:

• Participants who meet any of these criteria are not eligible for enrollment as study participants:
• Chronic disease (other than asthma, atopic dermatitis, rhinitis) requiring therapy (e.g., heart disease, diabetes)
• Participation in an interventional study*
• Inability to discontinue antihistamines for routine tests
• Children (other than sibling controls) from families with one child already participating in the observational study
• Confirmed or convincing evidence of peanut allergy

Sibling Inclusion Criteria for Mechanistic Studies:

• No history of food allergy (unrestricted diet), asthma, atopic dermatitis, allergic rhinitis (for blood sample)
• Full sibling of child enrolled in study
• Signed informed consent/assent as applicable

Sibling Exclusion Criteria in Mechanistic Studies:

• Not fulfilling inclusion criteria
• History of chronic anemia
• Disease or medication that impair immune responses

Sibling Inclusion Criteria for Genetic Testing:

• Full sibling of child enrolled in study
• Signed informed consent/assent as applicable

Sibling Exclusion Criteria for Genetic Testing:

• Not fulfilling inclusion criteria

Children with milk or egg allergy who are at risk for peanut allergy