TNF and tick-borne encephalitis: A review of the published information revealed that several cytokines are elevated during the second phase of TBE, including IL-1α, IL-2, IL-6, IL-8, IL-12, IL-15, IFN-α, IFN-γ, and TNF, and growth factors, such as hepatocyte growth factor and vascular endothelial growth factor in sera [12,21,27,30].