Intrathecal cytokines in systemic lupus erythematosus with central nervous system involvement

Symptoms originating from central nervous system (CNS) are frequently occuring in patients with systemic lupus erythematosus (SLE). Reliable diagnostic markers for this condition are presently lacking. Importantly, CNS involvement in lupus patients is associated with increased morbidity and mortality. The aim of this retrospective evaluate was to study the diagnostic value of cerebrospinal fluid (CSF) cytokine levels in SLE patients with CNS involvement. 34 patients with SLE were hospitalized and investigated for the presence of CNS lupus. These patients were evaluated clinically and with magnetic resonance imaging (MRI) and CSF analyses, as well as with neuropsychiatric tests. 13 patients were found to have CNS lupus whereas another four of the patients fulfilled the criteria for CNS involvement but were excluded from this group due to other causes of CNS involvement. Lastly, in 17 SLE cases, the diagnosis of CNS lupus could not be confirmed. CSF levels of interleukin-6 (IL-6) and IL-8, as well as the CSF/serum IL-6 ratio, were elevated in the CNS lupus group, compared with the 17 SLE patients not fullfilling a diagnosis of cerebral lupus. Interestingly, follow-up of five patients being successfully treated for CNS lupus revealed profound decrease of intrathecal IL-6 levels. These results indicate that analysis of CSF cytokine levels, especially IL-6 and IL-8, may be useful in the diagnostics and possibly follow-up of SLE patients with cerebral lupus.