D3.229 - Profiling Allergens in Onion and Garlic Shoots: A Case Study on Severe Food Allergy

Allergies to Allium species, such as onion (Allium cepa) and garlic shoots (Allium sativum), are rare but can manifest with severe reactions. This study investigates the allergenic profiles of raw and cooked onion and garlic shoots in a patient with a history of food-induced allergic symptoms.

A 34-year-old female presented with generalized urticaria, abdominal pain, and mild dyspnea 30 minutes after consuming a soup containing onion and garlic shoots. Skin prick tests were positive for Allium cepa and Allium sativum. The patient reported similar symptoms following the consumption of raw onion in salads but tolerated other vegetables and cooked dishes without Allium ingredients.

Protein extracts were prepared from raw and cooked onion and garlic shoots. SDS-PAGE and IgE-Western blot analyses were conducted under reducing conditions to assess allergenic profiles, using patient serum to identify specific IgE-binding proteins.

IgE-Western blot analysis revealed IgE binding to a ≈54 kDa protein in raw onion and garlic shoot extracts, likely corresponding to Alliin lyase, a known allergen in Allium species. Additionally, a 10–15 kDa protein was recognized in garlic shoot extracts and cooked onion, suggesting heat-stable allergenic properties.

This study identifies Alliin lyase and a smaller heat-stable protein as potential allergens in onion and garlic shoots. Detailed allergenic profiling is essential for accurate diagnosis and management, especially in patients with severe reactions to Allium species. Understanding the thermal stability of these allergens could inform dietary recommendations for sensitized individuals.