Immunocomplexes down-modulate the induction of food allergy in mouse through CD32b- and IL-21-dependent mechanisms. (55.7)

Abstract

Abstract Food allergy is an adverse Th2 response whose incidence has been increasing dramatically. Previously, we have demonstrated that immunocomplexes(IC) decrease the food allergic responses. Thus, we hypothesize that inhibitory FcR is triggered by IC in food allergy. Here we investigated the contribution of CD32b signaling in the down-modulatory effect of IC in a mouse food allergy model. Wild type(WT) or CD16-/- or CD64-/- or CD32b-/- or IL-21R-/-mice were sensitized by gavage for 8 weeks with SEB, SEB+OVA or SEB+OVA-IC and challenged on the 9th week with OVA. We demonstrated that OVA-IC-sensitized WT, CD16-/- or CD64-/- mice produced lower levels of serum IgE, IL-4, IL-5, and have decreased blood eosinophilia compared to OVA group. In contrast, OVA-IC-sensitized CD32b-/- mice did present food allergic responses similar to OVA group. In addition, IL-21 levels were high in OVA-IC-sensitized WT, CD16-/-, CD64-/- mice, but in CD32-/- mice, in comparison to OVA group. Besides, OVA-IC-sensitized IL-21R-/- mice restored the food allergic responses, similar to OVA group. In conclusion, IC down-regulates the food allergic response in WT, CD16-/-, CD64-/- mice but in CD32b-/- indicating that CD32b plays a role in the down-modulatory effect of IC. Besides, IC stimulate the production of IL-21 and up-regulate food allergic responses in IL-21R-/- mice, suggesting that down-modulation induced by IC is mediated by IL-21-dependent mechanism.