Soybean Isoflavones Suppress Basophil Degranulation in Vitro in Subjects with Food Allergy

Abstract

S U N D A Y 431 Soybean Isoflavones Suppress Basophil Degranulation in Vitro in Subjects with Food Allergy Mohanapriya Kamalakannan, MS, Matthew Stadler, Hugh A. Sampson, MD, FAAAAI, Madhan Masilamani, PhD; Mt. Sinai School of Medicine, New York, NY, Mount Sinai School of Medicine, New York, NY. RATIONALE: Soybean isoflavones, genistein and daidzein, are well known for their anti-inflammatory and immunomodulatory properties. We have recently shown that dietary isoflavones suppress anaphylactic reactions in murine models of peanut allergy. Here we tested the effect of isoflavones on human basophil degranulation in vitroin whole blood samples from subjects with food allergy. METHODS: Whole blood (250mL) from healthy controls (n53), and peanut allergic (n55) and milk allergic (n57) subjects were pre-incubated with 100mM each of genistein+daidzein for 30 min followed by culture with peanut or milk extracts respectively +/100mM genistein+daidzein for 30 min, as well as control stimulations such as anti-IgE, fMLP or medium alone. Degranulation was stopped by adding 20mM EDTA and stained for anti-CD63 and basophil-specific markers followed by flow cytometric analysis. Basophil degranulationwasmeasured by percent foldchange in CD63cells in the basophil gate. Phosphorylation of signal transduction molecules such as Erk, Syk and p38-MAP kinase in basophils was tested by flow cytometry. RESULTS: Isoflavones suppressed human basophil degranulation induced by anti-IgE cross-linking in a dose-dependent fashion. Basophil degranulation from peanut and milk allergic subjects was suppressed in vitro by allergen+isoflavone treatment when compared to allergen-treatment alone (mean % fold change5 217 vs 313 for peanut; 581 vs 949 for milk, respectively). Erk phosphorylation was also suppressed in isoflavone-treated basophils. CONCLUSIONS: Based on the in vitro data and our published results in peanut allergy in murine models, isoflavones may provide a novel treatment option for food allergy.