D1.69 - Safety in the peach juice food challenge in LTP allergic patients

Lipid transfer protein (LTP) allergy is a heterogeneous disease, which can present from mild symptoms located in the oral mucosa (OAS) to severe life-threatening reactions such as anaphylactic shock. The diagnosis and management of patients allergic to LTP is very complex, being the oral food challenge the gold standard that allows confirming the diagnosis. We performed a descriptive analysis of patients diagnosed with LTP allergy in our unit and their results in oral challenge with peach juice.

We selected patients diagnosed with allergy to peach LTP (Pru p 3), with skin prick test (SPT) positivity (papule >3mm2) and/or specific IgE (sIgE >0.35 kUA/L) by ImmunoCAP system. Skin tests were performed with peach extract enriched with Pru p 3. sIgE was analyzed using the ALEX multiplex analysis platform. A double-blind placebo-controlled food challenge (DBPCFC) was conducted with 200 ml of commercial peach juice, containing 1240 mcg of Pru p 3 and masked with other food until a total of 250 ml was obtained. We administered 6 doses with an initial dose of 5 mL.

25 patients (52% women) with a mean age of 29 years were included. 88% had rhinoconjunctivitis and/or asthma due to sensitization to aeroallergens. They had been diagnosed with LTP allergy between a few months and 8 years before the DBPCFC, although some patients reported symptoms since childhood.

10 patients had never had reactions with peach, but with nuts, 7 patients had contact pruritus/urticaria with the peel, 4 of them tolerating peeled intake and 11 had had reactions with ingestion (4 of them grade 1, 4 grade 2, 1 grade 3 and 2 grade 4 of the OFASS-5 classification).

4 patients who had previously been diagnosed with LTP allergy with positive sIgE to Pru p 3 in ImmunoCAP, had negative SPT for Pru ​​p 3, with sIgE levels <0.10 for Pru ​​p 3 in ALEX, however, they recognized other LTPs (Ole e 7, Zea m 14 and Cor a 8). Patients with positive SPT had a mean wheal area of ​​46mm. The sIgE mean was 5 kUA/L.

11 patients did not have any symptoms with DBPCFC, 7 presented grade 1 reactions, 6 patients had grade 2 reactions but only two required treatment, and one patient had a grade 4 reaction that improved with corticosteroid + anithistamine. There was no placebo reactors.

In our patients, performing the DBPCFC is very important since most of them presented mild and self-limited symptoms, which allows the avoidance of very restrictive diets by being able to differentiate between sensitization and allergy.