Determine Immunoglobulin G4 (IgG4) Standards for Cow's Milk and Egg in Different Populations of Allergic and Non-allergic Children

The study objectives are : Determine standards of plasma levels of casein-specific immunoglobulin G4 (IgG4) and egg-specific immunoglobulin G4 (IgG4) as a function of age, in non-allergic children, in allergic children, and in cured former allergic patients. Analyze the plasma IgG4 / IgE ratio, according to the result of the oral provocation test (tolerance versus allergy) and, in the event of a reaction, according to the reactogenic dose (dose which caused the reaction).Determine whether analysis of the plasma metabolome can identify children with a cured allergy to cow's milk protein or to egg from those with a persistent allergy.

Inclusion Criteria: * Minors aged 0 to 18 * In consultation or hospitalized for an oral food challenge for milk or eggs * To undergo a blood test Exclusion Criteria: Minors with immune deficiency, chronic inflammatory disease or immunosuppressive or immunomodulator treatment