Tick-borne encephalitis is associated with low levels of interleukin-10 in cerebrospinal fluid

Tick-borne encephalitis (TBE) is associated with higher morbidity and induces a stronger intrathecal immune activation than most other viral induced meningo-encephalitis. The aim of this study was to investigate cytokine concentrations in cerebrospinal fluid (CSF) and serum in relation to aetiology and clinical course. Cytokines were analysed by Enzyme-linked Immuno Assay (ELISA) from 44 patients with TBE and from 36 patients with aseptic meningo-encephalitis of other aetiology (non-TBE). Significantly increased CSF levels of Interferon-γ (IFN-γ), Interleukin-10 (IL-10), Interleukin-6 (IL-6), Interleukin-1 receptor antagonist (IL-1ra), and soluble CD8 receptor (sCD8) were detected in both cohorts. Tumour necrosis factor-α (TNF-α showed low levels or was not detected in CSF in any group in the acute stage. However, the CSF levels of IL-10 were significantly lower in TBE than in non-TBE cases 0-6 days after onset of encephalitis. The TBE patients with encephalitis had significantly lower IL-10 CSF levels later in the clinical course (day 7-18) than TBE patients with meningeal disease. Increased IFN-γ production, but low IL-10 secretion, may be of pathophysiological significance in TBE.