000334 - Catalase as a Potential Novel Allergen in Avocado: Proteomic Characterization in a Case of Immediate Digestive Reaction

Avocado (Persea americana) is an infrequent cause of IgE-mediated food allergy. Most reported cases are associated with latex–fruit syndrome, whereas isolated avocado allergy unrelated to latex sensitization remains uncommon and poorly characterized. The molecular basis of these reactions is largely unknown.

We describe the case of a 22-year-old woman with a history of dust-mite rhinoconjunctivitis who experienced two episodes of abdominal pain, nausea, and diaphoresis approximately 30 minutes after avocado ingestion. No cutaneous or respiratory involvement was observed. She had a previous positive test to tomato; however, current skin prick testing was negative for LTP, profilin, and latex, and showed a strongly positive prick-by-prick result with fresh avocado (10 mm).

Protein extracts from avocado, tomato, and kiwi were prepared following standard protocols. Allergenic profiling was performed by SDS-PAGE and IgE Western blot using the patient’s serum. IgE-reactive protein bands were subjected to in-gel digestion and molecular identification by LC-MS/MS.

IgE Western blot revealed a strongly reactive ~50 kDa band in the avocado extract. Proteomic analysis identified this protein as a catalase (ID: A0A3S3PH92_9MAGN). Catalase has been reported as an allergen in other plant sources but has not previously been described in avocado.

In tomato extract, three IgE-reactive bands of approximately 25 kDa were detected, whereas the kiwi extract showed only a faint signal corresponding to a ~60 kDa protein.

This case suggests that catalase may represent a previously unrecognized avocado allergen associated with immediate digestive symptoms. Molecular identification broadens the spectrum of plant-derived food allergens and underscores the value of proteomic approaches for delineating clinically relevant sensitization in molecular allergology.

Precise characterization of emerging allergenic proteins is essential to improve diagnosis and guide personalized management strategies.