Clinical analysis of cerebrospinal fluid interleukin-6 in neuropsychiatric systemic lupus erythematosus

To clarify the clinical usefulness of cerebrospinal fluid (CSF) interleukin-6 (IL-6) measurement in patients with neuropsychiatric systemic lupus erythematosus (NPSLE), we studied CSF IL-6 levels in patients with NPSLE and analyzed the association between CSF IL-6 levels and other clinical findings of NPSLE.We retrospectively analyzed records of 37 patients (33 females and four males) with NPSLE admitted to our hospital between January 2003 and December 2008.All patients showed neuropsychiatric symptoms. Fourteen patients showed abnormalities in brain magnetic resonance imaging (MRI) and 12 patients had abnormal findings in electroencephalography (EEG). Increased CSF cell counts and elevated levels of CSF IL-6 were found in 11 and 30 patients, respectively. Elevated levels of CSF IL-6 were not statistically correlated with specific abnormalities in the blood analysis, in increased CSF cell counts, and in abnormalities in the brain MRI and EEG. In addition, a group of NPSLE patients positive for antiphospholipid antibodies (aPL) showed lower CSF IL-6 than the patients negative for aPL.These results indicated that CSF IL-6 might be useful in diagnosis of NPSLE. However, general assessments of patients based on various factors (clinical manifestations, imaging findings and CSF examinations) are also required.