NEW FINDINGS suggest that the basophil activation test (BAT) may help identify children at highest risk of severe allergic reactions to cow’s milk and those who react to very small amounts. The study highlights BAT as a potentially valuable biomarker to improve risk stratification and management of one of the most common and dangerous food allergies worldwide.
Cow’s milk allergy is the leading cause of food allergy in children and a major trigger of fatal food-induced anaphylaxis. Oral food challenges (OFCs), the gold standard for diagnosis, carry inherent risks, particularly for patients prone to severe reactions or with a low threshold of reactivity. Identifying reliable biomarkers that can predict reaction severity and sensitivity before testing could significantly improve patient safety.
In this prospective analysis from the BAT2 study (NCT03309488), researchers assessed the severity and threshold of allergic reactions to baked milk (BM) and fresh milk (FM) during OFCs conducted according to international Practall guidelines. Demographic, clinical, and immunological parameters were compared between children with severe versus non-severe reactions, as well as those reacting at higher versus lower doses of milk protein.
Basophil Activation Test Identifies High-Risk Milk Allergy Patients
Of the 71 children that experienced allergic reactions during OFCs, 22 reacted to baked milk and 49 to fresh milk. Severe symptoms occurred in nearly one-third of baked milk reactors (32%) and around one-quarter of fresh milk reactors (24%). The median cumulative dose tolerated before reacting was 0.44 g of milk protein for baked milk and just 0.143 g for fresh milk, highlighting the lower reaction threshold for unheated milk.
Among all parameters studied, BAT was the only biomarker able to distinguish both reaction severity and reaction threshold. Specific BAT cut-off values identified children at risk of severe reactions to baked milk with 71% sensitivity and 100% specificity. For fresh milk, BAT identified children reacting to very small amounts (≤0.143 g) with high sensitivity (96%), although specificity was more modest (41%).
Findings Highlight Potential for Personalised Allergy Care
Notably, commonly used clinical and immunological markers did not reliably predict either severity or threshold, underscoring the unique value of BAT in this setting. The authors highlight that clinical application of BAT would allow stratification of patients allergic to cow’s milk and therefore improve how their allergy is managed.
Reference
Boyd H et al. Basophil Activation Test as Biomarker of Severity and Threshold of Allergic Reactions to Cow’s Milk During Oral Food Challenges. Allergy.2025;doi: 10.1111/all.70175
