Specific IgE to peanut 2S albumin Ara h 7 has a discriminative ability comparable to Ara h 2 and 6

Abstract

Background

Little is known on the clinical relevance of peanut 2S albumin Ara h 7.

Objective

To investigate the discriminative ability of Ara h 7 in peanut allergy and assess the role of cross-reactivity between Ara h 2, 6 and Ara h 7 isoforms.

Methods

Sensitization to recombinant peanut storage proteins Ara h 1, 2, 3, 6 and 7 was assessed using a line blot in sera from 40 peanut tolerant and 40 peanut allergic patients, based on food challenge outcome. A dose-dependent ELISA inhibition experiment was performed with recombinant Ara h 2, 6 and Ara h 7 isoforms.

Results

For Ara h 7.0201 an area under the ROC curve was found of 0.83, comparable to Ara h 2 (AUC 0.81) and Ara h 6 (AUC 0.85). Ara h 7 intensity values strongly correlated with those from Ara h 2 and 6 (r_s=0.81). Of all patients sensitized to 2S albumins Ara h 2, 6 or 7, the majority was co-sensitized to all three (n=24, 68%), although mono-sensitization to either 2S albumin was also observed in selected patients (Ara h 2: n=6, 17%; Ara h 6: n=2, 6%; Ara h 7: n=2, 6%). Binding to Ara h 7.0101 could be strongly inhibited by Ara h 7.0201, but not the other way around.

Conclusions & Clinical Relevance

Specific IgE against Ara h 7.0201 has a predictive ability for peanut allergy similar to Ara h 2 and 6, and possesses unique IgE epitopes as well as epitopes shared between the other Ara h 7 isoform and Ara h 2 and 6. While co-sensitization to all three 2S albumins is most common, mono-sensitization to either Ara h 2, 6 or 7 occurs in selected patients, leading to a risk of misdiagnosis when testing for a single 2S albumin.

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