1. IL-10 is involved in regulation of the middle ear inflammatory response induced by bacterial infection. 2. The expression of IL-10 in acute otitis media is up-regulated shortly after or even simul- taneously with the pro-inflammatory cytokines, TNF-a and IL-6. That is, the evidence of initiation of corrective immunoregulation in the middle ear mucosa, because IL-10 as the main anti-inflammatory cytokine, can down-regulate the local population of inflammatory cells, macrophages and neutrophils, and production of the proinflammatory cytokines TNF-a, IL-1b, IL-6, IL-8 and promote resolution of inflammation (Fig. 2 ). 3. If the acute inflammatory response is not resolved correctly, the prolonged presence of IL-10 in the zone of inflammation can provoke the amplification of chronic humoral inflammatory processes, such as increased secretion of immunoglobulins, especially IgA, by activated B cells and possible generation of plasma cells, in the presence of IL-4 ( Fig. 4) . In this way, IL-10 can contribute to switching of the disease into the chronic stage. 4. The deficiency of IL-10 in acute otitis media can also lead to chronic condition of OME, because shortage of IL-10 will promote overproduction of the inflammatory cytokines, especially IL-1b, TNF-a and IL-6, which can induce tissue damage and irre-versible changes in the middle ear mucosa (Fig. 4) .