This idea is reinforced by findings of elevated levels of Th-2 cytokines, such as IL-4, IL-5, and IL-13, and the presence of mast cells and their mediators, including tryptase, in the middle-ear effusion, which indicates that allergic inflammation could contribute to the persistence of OME [56,57,58,59,60,61]. Here, IL13 is linked to otitis media with effusion.