Wallowitz ML, Chen RJ, Tzen JT, Teuber SS.
Clin Exp Allergy. 2007 Jun;37(6):929-38.
Department of Internal Medicine, Division of Rheumatology, Allergy and Clinical Immunology, School of Medicine, University of California, Davis, CA 95616, USA.
BACKGROUND: Sesame allergy is increasingly being reported, and multi-sensitization to peanut and tree nuts has been described. The clinical relevance and cross-reactivity of many sesame proteins, such as Ses i 6, are unknown. OBJECTIVE: The aims of this study were to perform a preliminary examination of the cross-reactivity of Ses i 6 in vitro, examine the ability of Ses i 6 to activate basophils in a modified basophil activation test (mBAT), and assess whether such an assay may help to distinguish between potentially relevant and irrelevant IgE reactivity towards 11S globulin proteins. METHODS: Inhibition immunoblotting and chicken anti-rJug r 4 antibodies were used to determine the cross-reactivity of rSes i 6. Basophils from atopic donors were stripped of resident IgE before passive sensitization with food-allergic sera and challenged with protein extracts or recombinant protein. Basophil activation was measured using two activation markers, CD203c and CD63, via flow cytometry. RESULTS: IgE immunoblotting showed cross-reactivity between rJug r 4 and rSes i 6 using sera from two human donors and chicken IgY. Additionally, rSes i 6 activated basophils passively sensitized with sesame-allergic sera. Cross-reactive serum from a sesame-allergic but walnut-tolerant donor was not able to activate basophils when challenged by walnut extract despite IgE reactivity to walnut determined by immunoblotting. CONCLUSIONS: The sesame 11S globulin shows partial immunological cross-reactivity with walnut, and although it is classified as a minor allergen, activated basophils sensitized with serum from seven out of eleven sesame-allergic donors. Additionally, the mBAT may help distinguish between clinically relevant and irrelevant in vitro IgE cross-reactivity of seed storage proteins in nuts and seeds and thus warrants use in further studies.