Dietary flavones suppresses IgE and Th2 cytokines in OVA-immunized BALB/c mice

Background: The flavonoids are a diverse family of chemicals commonly found in fruits and vegetables. Previously, we have shown that the two flavones, chrysin and apigenin could suppress the expression of the high affinity IgE receptor FcεRI in human basophilic KU812 cells. We also demonstrated that dietary apigenin decreased IgE level in C57BL/6N mice sera. Aim of the study: To evaluate the anti-allergic effect of the two flavones in vivo, we evaluated the effect of the two flavones, chrysin and apigenin, on the immune system in BALB/c mice sensitized with ovalbumin (OVA). Methods: Mice were fed experimental diets containing either of the flavones for 3 weeks and immunized with OVA. After the experimental feeding period, measurement of Igs concentration in the mice sera was performed using a sandwich ELISA. Cytokines expression in mice sera was assessed using a cytokine array. Furthermore, cytokines mRNA levels in spleen lymphocytes from mice sensitized with OVA were measured by RT-PCR. Results: The total IgE level in mice fed one of the two flavones were suppressed, whereas levels of IgG, IgM, and IgA were not affected. The production of interleukin (IL)-4, which is known as one of Th2 cytokines and regulates the production of IgE, was down-regulated by the chrysin or the apigenin diet. Moreover, OVA-induced mRNA expression of Th2 cytokines in spleen lymphocytes from mice sensitized with OVA, such as IL-4 and IL-13 were down-regulated by the chrysin or the apigenin diet. Conclusions: The results suggest that the diet containing one of the two flavones might suppress the up-regulation of serum IgE induced by OVA-immunization through the suppression of Th2-type immune response.