Increased levels of interleukins 2 and 17 in the cerebrospinal fluid of patients with idiopathic intracranial hypertension.

IIH is a condition of raised intracranial pressure of unknown pathogenesis, which is most commonly seen in young overweight women. This study was designed to confirm and extend previous reports by our and other groups showing increased inflammatory cytokine expression in patients with IIH. We analyzed the concentrations of 14 cytokines (IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-17, IL-22, IL-23, IFNγ, TNFα, TGFβ, and osteopontin) in the serum and cerebrospinal fluid (CSF) of 17 patients with IIH and 53 patients with other neurological conditions. Patients with IIH had highly elevated IL-2, IL-4, IL-10, IL-17 and IFNγ in the CSF compared to patients with multiple sclerosis or non-organic/non-inflammatory neurological conditions. No significant differences were seen between serum cytokine levels in four patient groups (IIH - multiple sclerosis - inflammatory neurological conditions - non-organic/non-inflammatory neurological conditions) and there were no correlations between serum and CSF cytokine levels. In IIH, levels of IL-2, IL-8 and IL-17 were significantly higher in CSF than serum; levels of IL-1β, IL-4, IL-22, IFNγ and TNFα were significantly higher in serum than CSF. For most cytokines, the CSF/serum cytokine ratio was significantly higher than the CSF/serum albumin ratio, indicating intrathecal synthesis of these cytokines in IIH. We conclude that IIH is associated with elevated levels of IL-17 and IL-2 in the CSF, suggesting the involvement of these cytokines in disease pathogenesis.