D2.10 - Early-onset cow’s milk protein and tree nut allergy: the value of component-resolved diagnosis in interpreting low-level alpha-gal sensitization
Case report
Background
Cow’s milk protein allergy (CMPA) is the most common food allergy in infancy, while tree nut allergy carries a higher risk of severe and persistent reactions. The coexistence of multiple food allergies early in life poses diagnostic challenges, particularly when sensitization to mammalian-derived allergens and alpha-gal is detected.
Case presentation:
We report a 2-year-old child who developed gastrointestinal symptoms after cow’s milk introduction, followed by generalized urticaria after ingestion of cashew and pistachio. At 2.5 years, cashew ingestion triggered angioedema requiring systemic corticosteroid treatment.
Methods:
Total and specific IgE were measured using ImmunoCAP (Thermo Fisher Scientific), complemented by component-resolved diagnostics. Cow’s milk evaluation included α-lactalbumin, β-lactoglobulin, and casein; tree nuts included walnut, cashew, pistachio, and hazelnut, with storage proteins (Jug r 1, Ana o 3) and lipid transfer protein (Jug r 3). Sensitization to beef, serum albumin (Bos d 6), egg proteins, and alpha-gal was also assessed.
Results:
Total IgE was elevated (317 kUA/L). Specific IgE to cow’s milk and its major components were positive (casein 2.5–8.5 kUA/L). Tree nut-specific IgE were positive, with molecular analysis confirming storage protein sensitization (Jug r 1 2.4 kUA/L; Ana o 3 10.4 kUA/L) and negative LTP (Jug r 3 0.01 kUA/L). Beef and Bos d 6 IgE were positive. Alpha-gal–specific IgE was low-level positive (0.19 kUA/L), without delayed reactions.
Conclusion:
This case illustrates an uncommon early-childhood combination of CMPA and tree nut allergy. Molecular diagnosis clarified the sensitization profile, confirmed clinically relevant storage protein reactivity, and interpreted low-level alpha-gal sensitization, arguing against a clinically significant alpha-gal syndrome. This approach allowed personalized dietary management while avoiding unnecessary restrictions.
