Elevation of cerebrospinal fluid interleukin-6 activity in patients with vasculitides and central nervous system involvement.

The pathogenesis of central nervous system (CNS) involvement in vasculitides remains unclear. We evaluated cerebrospinal fluid (CSF) interleukin-6 (IL-6) activity in relation to the CNS disease activity in vasculitides. Three patients with vasculitides of different categories who showed CNS manifestations were studied, including polyarteritis nodosa, temporal arteritis, and Behcet's disease. All three patients showed marked elevation of CSF IL-6 activity in parallel with the CNS disease activity. In one of the three patients, cerebral vasculitis was demonstrated histologically. All these patients also showed elevation of serum IL-6 activity in parallel with systemic symptoms, such as fever and/or elevation of C-reactive protein and erythrocyte sedimentation rate. These results strongly suggest that elevation of CSF IL-6 activity may underly the common pathogenetic mechanism of CNS involvement of vasculitides irrespective of their category. Taken together with the histopathological findings in one patient, the data also suggest that inflammation might not be restricted within the CNS blood vessels, but rather be extended to brain parenchyma to promote IL-6 production presumably by glial cells.