Studies on IL-4 in experimental OME 93,112 demonstrated the involvement of IL-4 in regulation of different types of otitis media. In trans-tympanically challenged animals the expression of IL-4 was detected during acute and chronic otitis media, with the predominance of IL-4 ' cells in the acute form. 93 The trans-tympanical injection of soluble receptors for IL-4 prevented the allergic Eustachian tube dysfunction and formation of effusion in the middle ear cleft. 112 The involvement of IL-4 in regulation of MUC5AC and MUC5B mucin gene expression and secretion has been shown in human airways. 113 Á 115 The secreted mucins, MUC5AC and MUC5B, are presented in the middle ear mucosa and effusions in patients with chronic OME. 53,55,57 Á 60 Although relationships between IL-4 and production of MUC5AC and MUC5B mucins in the course of otitis media have not been investigated, the ability of a soluble receptor for IL-4 to prevent Eustachian tube dysfunction and formation of effusions in the middle ear cleft 112 demonstrated the potential involvement of IL-4 in the regulation of the middle ear mucin metabolism.