Basophil Activation Test to Diagnose Food Allergy

1. Children ≥6 months and \<16 years old;

2. Suspected IgE-mediated food allergy defined by:

   • History of an immediate-type allergic reaction to a specific food or
   • No history of consumption of the specific food or
   • IgE sensitisation documented by skin prick test (≥1 mm) or serum specific IgE (≥0.10 KU/L);
3. Avoidance of the specific food for at least 2 days prior to blood collection for BAT and specific IgE and prior to the challenge;
4. Informed consent obtained from parent or guardian and assent obtained from the child.

Exclusion Criteria:

1. Clinically significant chronic illness other than atopic diseases;
2. 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;
3. Unwillingness to comply with study procedures, namely to undergo a diagnostic food challenge;

4. 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;
5. Undergoing treatment with omalizumab, food allergen immunotherapy or other systemic immunomodulatory treatment;
6. Inability to stop anti-histamines prior to SPT.