The immunoregulatory cytokines IL-2, IL-10 and TGF-b initiate and support molecular switching of the acute phase of inflammation in the chronic stage, whereas the allergy-associated cytokines IL-4, IL-5 and GM-CSF very probably provide the molecular and cellular background for chronic humoral, cell-mediated and allergic inflammatory processes in the middle ear, which lead to the chronic condition of OME.