Publications

Background The peanut allergens Ara h 2, h 6, and h 7 are potent allergens and can trigger severe reactions. Ara h 7 consists of three isoforms differing in their ability to induce basophil degranulation, whereas the ability of Ara h 7.0201 is comparable to Ara h 2 and 6 as shown in previous literature. Objective To identify linear epitopes of Ara h 7.0101, Ara h 7.0201 and Ara h 7.0301 recognized by IgE and IgG4 from patients sensitized to Ara h 7 and to investigate their potential to elucidate divergent abilities of the Ara h 7 isoforms in inducing basophil activation. Methods Linear epitopes recognized by IgE and IgG4 were mapped by peptide microarray analysis containing 15-mer peptides of Ara h 2.0201, 6, 7.0101, 7.0201 and 7.0301 and 39 peanut allergic patients sensitized to Ara h 7 (discovery). For validation, 20-mer peptides containing the minimal epitope and surrounding amino acids were incubated with 25 sensitized patients and 10 controls (validation). Results Three out of 14 linear epitopes were unique for each isoform (Ara h 7.0101: aa 97-109; Ara h 7.0201: aa 122-133; Ara h 7.0301: aa 65-74) but scarcely recognized by IgE. The main linear IgE epitope (aa 51-57) located in the long flexible loop of all Ara h 7 isoforms was bound by antibodies from 31% of the patients (discovery and validation cohort). Regarding IgG4, 55% of the patients recognized an epitope present on all isoforms (aa 55-65), whereas epitope aa 129-137, only present on Ara h 7.0101/0.0301, was recognized by 38% of the patients. Recognition was highly individual, although 20% of the patients recognized any linear epitope neither by IgE nor by IgG4 despite a low mean z-score of ≥ 1.7. Remarkably, only 50% of the patients recognized one or more epitopes by IgE. Conclusion & Clinical Relevance Ara h 7 isoforms share many linear epitopes being easily accessible for antibody binding. Unique epitopes, essential to elucidate divergent potencies, were scarcely recognized, suggesting a crucial involvement of conformational epitopes.

Background The precise mapping of multiple antibody epitopes recognized by patients’ sera allows a more detailed and differentiated understanding of immunological diseases. It may lead to the development of novel therapies and diagnostic tools. Objective Mapping soy bean specific epitopes relevant for soy bean allergy patients and persons sensitized to soy bean, and analysis of their IgE/IgG binding spectrum. Methods Identification of epitopes using sera, applying an optimized peptide phage display library followed by next-generation sequencing, specially designed in silico data analysis and subsequent peptide microarray analysis. Results We were able to identify more than 400 potential epitope motifs in soy bean proteins. More than 60% of them have not yet been described as potential epitopes. Eighty-three peptides, representing the 42 most frequently found epitope candidates, were validated by microarray analysis using 50 sera from people who have been tested positive in skin prick test (SPT). Of these peptides, 56 were bound by antibodies, 55 by serum IgE, 43 by serum IgG and 30 by both. Person-specific epitope patterns were found for each individual and protein. Conclusions For individuals with clinical symptoms, epitope resolved analyses reveal a high prevalence of IgE binding to a few soy bean specific epitopes. Evaluation of individual immune profiles of patients with soy bean sensitization allows the identification of peptides that do facilitate studying individual IgE/IgG epitope binding patterns. This enables discrimination of sensitization from disease, such assay test has the potential to replace SPT assays