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

• Published in: Clinical and experimental allergy 2018-01, Vol.48 (1), p.60-65
• Main Authors: Blankestijn, M. A., Otten, H. G., Suer, W., Weimann, A., Knol, E. F., Knulst, A. C.
• Format: Article
• Language: English
• Subjects: 2S albumin; Albumin; Ara h 1 antigen; Ara h 2; Ara h 2 antigen; Ara h 6; Ara h 7; Cross-reactivity; Enzyme-linked immunosorbent assay; Epitopes; Food allergies; food allergy; Immunoglobulin E; Isoforms; peanut allergy; Proteins; Storage proteins
• ISSN: 0954-7894; 1365-2222
• DOI: 10.1111/cea.13030

Summary 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 (rs = 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 and 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.