D1.301 - Non-specific lipid transfer protein allergy: the culprit in disguise

Non-specific lipid transfer proteins (nsLTP) allergy is a plant-food allergy commonly found in Southern Europe. Diagnosis can be challenging, and high clinical suspicion is required.

A 42-year-old female was referred to our Allergy Department due to an episode of anaphylaxis 1 hour after taking amoxicillin 1g and ibuprofen 600mg for tonsillitis (day 2 of treatment). She had eaten rice with squid 2 hours prior.

In the Emergency Department (ED) she was treated with intramuscular adrenaline, intravenous antihistamines and corticosteroids. Serum tryptase levels were not measured. Amoxicillin and ibuprofen avoidance was advised.

Later, she tolerated ibuprofen (600mg) and the aforementioned foods.

Skin prick tests (SPT) were positive to dust mites and plane tree and negative for crustacean and molluscs.

Serum-specific immunoglobulin E (sIgE) to beta-lactams were negative (sIgE <0.35 kIU/L). SPT and intradermal tests (IDT) with commercial kit for major (PPL) and minor determinants (MDM) in penicillin and amoxicillin were negative. SPT and IDT with amoxicillin clavulanate, penicillin and cefuroxime were negative. Baseline tryptase was 7ug/L. Drug provocation tests (DPT) to cefuroxime and amoxicilin were negative.

During follow-up, she presented a new episode of anaphylaxis minutes after eating peanuts and cashew, with no concomitant drugs.

Workup diagnosis was reviewed and she presented positive SPT to almond, peanut, cashew and to LTP extract and Tri a 14, Ara h 9, Jug r 3, Art v 3, Ole e 7 and Pla a 3 (ImmunoCAP™ ISAC assay).

A careful food history was remade and the patient avoided peach since childhood for taste reasons. On the first reaction, she remembered drinking flavoured water (with apple as an hidden allergen). Although she tolerated peeled apple daily.

She was advised to avoid peanut, tree nuts, peach and unpeeled apple. An adrenaline auto-injector, prednisolone and ebastine were prescribed in case of allergic reaction.

This case highlights the diagnostic complexity of nsLTP allergy and co-factor enhanced food allergy (CEFA), particularly when initial symptoms overlap with potential drug-induced anaphylaxis.

LTP syndrome is a complex clinical pattern and should be considered in the presence of idiopathic anaphylaxis, CEFA or nonsteroidal anti-inflammatory drug intake.

Even when drug allergy is suspected, food intake in the preceding 2 hours should always be asked.