Are 30-min time intervals between dose steps in oral food challenges adequate? Results based on the passive transfer of IgE-mediated cutaneous reactivity in heterologous subjects

Background: Oral food challenges is the gold standard for diagnosing food allergy. Most diagnostic centres have implemented standard operating procedures for such challenges including fixed time intervals between dose steps. Recently, concerns have been raised that 30-min intervals is too short. This would imply that oral food challenges are not as safe and harm free as they could be and further that the eliciting dose for patients might not always be correctly determined. We present a study based on the principles of the original experiments by Prausnitz and Kustner. The aim was to study whether 30 min between dose steps during oral challenge with roasted peanut is adequate or not. Method: A group of patients (n= 4) with allergy to peanut volunteered to donate blood for experimental purposes. Their SIgE profiles to peanut differed including specific S-IgE to Ara h 2, ranging from two to 71 10E3 IU/L (ImmunoCAP, Thermo Fischer Scientific, Uppsala, Sweden). After approval from the local ethics committee and appropriate testing for safety reasons, the four sera were used for heterologous, passive transfer of IgE (priming). This was carried out by means of intradermal injections of 0.1 ml serum into the volar forearms of non-allergic volunteers (n= 12). Twenty-four hour following priming, the subjects underwent an oral challenge (single-shot) with 10 g of roasted peanut. Results: In the majority of the subjects (n= 11 out of 12), the first signs of a whealand- flare reaction appeared in