D1.180 - Mandarin-Induced Allergic Reactions: A Case Study Investigating Germin-Like Proteins and Cross-Reactivity

Citrus allergies, though uncommon, can manifest with severe systemic allergic symptoms. Germin-like proteins (Cit s 1) have been identified as potential allergens in citrus fruits. This study investigates a case of mandarin-induced allergic reactions to identify specific allergenic proteins and their cross-reactivity with related allergens.

A 39-year-old woman with a history of hazelnut allergy and allergic rhinoconjunctivitis due to animal epithelia, dust mites, and plane tree pollen experienced recurrent episodes of urticaria, angioedema, gastrointestinal symptoms, and tachycardia following the consumption of mandarins. Prick-by-prick tests were positive for mandarin, orange, lemon, and eggplant. The results suggested potential sensitization to lipid transfer proteins (LTPs) and cross-reactivity with other allergens.

Protein extracts from mandarin, orange (skin and pulp), and eggplant (raw and cooked) were analyzed using SDS-PAGE and Western blot under reducing and non-reducing conditions to assess protein and allergenic profiles. Inhibition assays were conducted to evaluate cross-reactivity with plane tree pollen and hazelnut.

IgE-Western blot revealed strong binding to a 25 kDa protein in mandarin and orange skin extracts under both reducing and non-reducing conditions, with stronger intensity under reducing conditions. The protein was identified as a germin-like protein (Cit s 1 in orange and its mandarin analog). Inhibition assays confirmed cross-reactivity between mandarin skin proteins and plane tree pollen and hazelnut. No significant IgE reactivity was observed with eggplant extracts.

This case highlights germin-like proteins as key allergens in citrus-induced allergies, with potential cross-reactivity to plane tree pollen and hazelnut. Comprehensive allergenic profiling is essential for accurate diagnosis and tailored management of citrus and related food allergies. Further research on germin-like proteins will enhance understanding and guide prevention strategies.