Germin: Relevant Allergen in Lemon, Orange and Mandarin

Orange allergy is estimated to account for 3% of food allergies. Cit s 1 (germin-like protein) and Cit s 2 (profilin) have been identified as major allergens. Also, Cyt s 3 (lipid transfer protein) and Cyt s 7 (gibberellin-regulated protein) have been described as orange allergens. This study focuses on the unusual occurrence of orange allergy in five patients. Materials and methods: We report five cases of patients with immediate allergic manifestations after ingestion of orange. Skin prick-tests to common aeroallergens, and different foods. Prick by prick with orange, lemon pulp mandarin (peel, pulp and seeds). Anaphylaxis score; Total IgE, Serum-specific IgE and food allergy quality of life questionnaire. Allergenic extracts were prepared from orange (Citrus sinensis), lemon (Citrus lemon) and mandarin (Citrus reticulata) peel and pulp. Protein characterization was determined by Bradford and SDS-PAGE and sera by immunoblot. Selected proteins were identified by peptide fingerprinting. Results: A 23 kD band was recognized by all 5 patients in orange (pulp and peel), lemon (peel) and mandarin (pulp and peel), having already been annotated in IUIS in the case of orange as germin (Cit s 1). To send the 23 kDa bands for peptide fingerprinting, SDS-PAGE of the 3 fruits was performed and as a positive control we used the 23 kDa band from orange. Together, the 23 kDa bands from orange, lemon and mandarin peel were cut out and sent for peptide fingerprint analysis, yielding the germin like protein sequence in all cases. Conclusions: A band of 23 kDa (germin-like protein) appears common in orange (annotated in IUIS as germin), lemon and tange-rine peel. Not previously described in IUIS in lemon and mandarin and confirmed as germin. Germin was in the peel of the 3 fruits and in the orange pulp, but not in lemon or mandarin.