The Clinical Impact of the Basophil Activation Test to Diagnose Food Allergy

Inclusion Criteria: * Children and young people aged 6 months to 15 years * Suspected allergy to one of the study foods (peanut, cow's milk, egg, cashew, sesame) - defined as: * history of clinical reaction or * evidence of IgE sensitisation (SPT\>0mm and/or specific IgE\>=0.10 KU/L) to the respective food or * reassessment for possible resolution of allergy to the specific food following previous diagnosis of food allergy * Need for an oral food challengeOFC to the study food * Oral food challengeOFC to reach amount of food protein in a typical portion size for child's age * Consent from adults with parental responsibility and assent from children and young people in an age appropriate form. Exclusion Criteria: * Clinically significant chronic illness other than atopic diseases; * Previous history of severe life-threatening reaction to the suspected food with documented decrease in oxygen saturation (\<90%), hypotension (≥20% reduction in systolic blood pressure) and/or admission to intensive care; * Unwillingness to comply with study procedures, namely to undergo a diagnostic food challenge; * Contra-indication for diagnostic food challenge, namely: * Uncontrolled atopic diseases (e.g. eczema, asthma, rhinitis); * Chronic medical conditions that pose significant risk in the event of anaphylaxis or treatment of anaphylaxis (e.g. cardiac disease, severe lung disease, pregnancy, mastocytosis); * Inability to discontinue medications that might interfere with assessment or safety (e.g. antihistamines, β-agonists, β-blockers, NSAIDs, ACE inhibitor, antacids); * Recent (within 7-14 days) treatment with systemic steroids or prolonged high-dose systemic steroids or immunosuppressants; * Undergoing treatment with omalizumab, food or inhalant allergen immunotherapy or other systemic immunomodulatory treatment; * Inability to stop anti-histamines prior to SPT or OFC.