This is a multi-centered observational study comparing the safety and compliance of different procedures for introducing tree nuts into the diet of patients with IgE-mediated allergy to nuts. The effectiveness of tree nuts' introduction in respect to tolerance induction compared to the standard care (strict avoidance of tree nuts) will also be evaluated.
The study will be contacted in the Department of Allergy and Clinical Immunology, 2nd University Pediatric Clinic of "Panagiotis \& Aglaia Kyriakou" Children's Hospital, Athens, Greece, in collaboration with the Allergy Unit "Dimitrios Kalogeromitros, 2nd University Clinic of Dermatology and Venereology, "Attikon" University Hospital, University of Athens, Greece and the Allergology Department of "Laiko" General Hospital, Athens, Greece.
The study will include participants with persistent IgE mediated allergy to tree nuts (including at least walnut or pistachio) who are willing to follow one of the two induction procedures (A: at home, B: at the hospital) and voluntarily provide written consent in the procedures and the goals of the study. Participants will adhere to one of the two induction procedures according to their preferences. Groups will be matched in respect to the number of participants.
Participants who have already followed one of the two procedures can participate following written informed consent.
The control group consists of participants who do not wish to introduce tree nuts into their diet but will consent to provide their medical data and the results of their allergology work-up for research purposes. The target ratio between active and control groups will be 3:1.
Introduction of Tree Nuts consists of:
Baseline Assessment (Screening period):
In all participants, active and control, IgE-mediated allergy is evaluated by Skin Prick Tests (SPTs), serum specific IgE (sIgE) to tree nuts, serum sIgE to tree nuts' components and Basophile Activation Test (BAT) to the implicated tree nut and is confirmed by oral food challenges (OFC) with the nut. Additionally, total IgE and tryptase levels are assessed.
Tree Nuts' Introduction Phase:
Commercially available drinks of the respective tree nut, in suitable dilutions, are used for the introduction.
First day of introduction: Participants in both active groups (procedures A and B) receive the first dose of the drink in the hospital under specialized medical observation.
Escalation period: Drinks in suitable dilutions are given daily to participants. Dose escalation is performed at weekly intervals at home (procedure A) or every 2 months at the hospital (procedure B) until reaching maintenance dose or patient's maximum tolerated dose. The escalation period is estimated at 64 weeks (16 months). The up-dosing scheme and maintenance dose and duration will be adjusted in case of adverse allergic reactions.
Maintenance Phase: The maintenance starts when participants reach the maintenance dose or their maximum tolerated dose, and lasts for at least 4 weeks.
Participants in the control group are instructed to strictly avoid offending tree nuts, as per standard care.
During Tree Nuts' Introduction Phase all participants, active and control, will be followed up periodically in two months intervals.
Final Assessment:
After completing at least 4 weeks at maintenance phase all participants will undergo an open oral food challenge with the offending nut(s) to assess tolerance. SPTs, total IgE, serum sIgE to tree nuts, serum sIgE to tree nuts' components and Basophile Activation Test (BAT) to each tree nut the participant is allergic will be re-evaluated.
