Figure 2. Potential immune mechanism of IgE-mediated food allergy by collaboration of MMC9, ILC2 and CD4⁺Th2. Intestinal epithelium produces IL-25 by ingested food proteins. With differentiated Th2 cells, ILC2s produce IL-5 and IL-13 in response to IL-25 and induce eosinophilia and goblet cell hyperplasia. With differentiated Th2 cells, MCP develop into MMC9. IL-9 production by MMC9 drives MMC9 maturation into MMC. Addition to classical IgE-mediated food allergy mechanism, new cytokines like IL-25 and IL-9 and new cells like ILC2 and MMC9 mediate to initiate food allergic response and to govern susceptibility to IgE-mediated food allergy.