IL6 and tick-borne encephalitis: Similarly as previously reported for nonvaccinated TBE patients, we observed a systemic upregulation of some proinflammatory cytokines in VBT patients, yet the majority of them, including IFN-α2, IFN-β, IL-6, IL-8, IL-15, MCP-1/CCL-2, and MIP-3β/CCL19, was significantly higher in CSF, suggesting their upregulated production at the primary site of infection in the 2nd phase of the disease.