1. IL-2 is involved in regulation of the middle ear inflammation and, as the main T-cell growth and differentiation factor, IL-2 can support acute and chronic inflammatory processes in the middle ear. 2. IL-2 can regulate local acute inflammatory response by inducing activation, differentiation of T cells and production of the proinflammatory (IL-1b, IL-6) and anti-inflammatory cytokines (IL-10, TGF-b) by activated T cells (Fig. 2 ). 3. The deficiency of local or general IL-2 production can suppress reactions of acute inflammation and promote persistence of OME, which can develop with time into the chronic OME (Fig. 3 ). 4. The excessive production of IL-2 can provoke chronic cell-mediated and (or) humoral inflammatory processes (proliferation of activated T cells, increased production of cytokines IL-4, IL-5 and GM-CSF by proliferated T cells, immunoglobulin-switching and IgM secretion in B cells), which will induce switching of the middle ear inflammation in the chronic stage with subsequent development of chronic OME (Fig. 3) . 