IL-5 is an important regulator of the humoral immune response and is produced by CD4 ' T cells as well as NK cells. 24 Being a late regulating factor in differentiation of B cells, IL-5 plays an essential role in cytokine-induced production and secretion of immunoglobulins and supports humoral inflammatory reactions such as production and secretion of IgA. 25 IL-5 is also the allergic cytokine, which by stimulating production, activation, differentiation and migration of eosinophils creates a strong molecular background for eosinophilic inflammation. 26, 27 GM-CSF regulates proliferation and maturation of granulocyte and macrophage precursors and activates mature neutrophils, eosinophils and macrophages, 28 and thus participates in different types of inflammation. 29 Monocytes, T cells, fibroblasts and endothelial cells activated by macrophage cytokines IL-1b or TNF-a produce GM-CSF. The GM-CSF enhances neutrophil phagocytosis, enhances release of chemotactic factors by neutrophils, 30 induces production of the pro-inflammatory cytokines by macrophages and increases their function as antigen-presenting cells, 31 and in this way promotes acute inflammatory reactions. In the presence of IL-4, GM-CSF can initiate a specific differentiation of monocytes into osteoclast-like multinucleated giant cells 32 that create a background for chronic inflammation. GM-CSF can also contribute to allergic inflammation by promoting growth, prolonged survival and activation of eosinophils and basophils. 33 Both groups of cytokines, the immunoregulatory IL-2, IL-10 and TGF-b and the allergy-associated IL-4, IL-5 and GM-CSF, have been identified in otitis media and their presence is the evidence of their participation in regulation of local inflammatory processes. These cytokines can switch the acute phase of middle ear inflammation into the chronic stage and lead to the chronic condition of otitis media with effusion (OME). OME: a brief description OME, the commonest cause of childhood deafness in the developed world, is a chronic inflammatory condition of the middle ear cleft with repetitive recurrences of acute middle ear inflammation. The disease is characterized by a middle ear effusion that persists for months to years, cannot be cleared by the normal mucociliary transport mechanisms and is must usually removed by surgical operation.