The heterogeneity of neuropsychiatric systemic lupus erythematosus is reflected in lack of association with cerebrospinal fluid cytokine profiles.

The objective was to study the occurrence of autoantibodies and cytokines in serum and cerebrospinal fluid (CSF) in neuropsychiatric systemic lupus erythematosus (NPSLE). In total, 28 consecutive patients with NPSLE and 16 systemic lupus erythematosus (SLE) patients without neuropsychiatric involvement (non-NPSLE) were studied. IFN-alpha, IL-6, IL-10, soluble terminal complement complex (TCC), anti-ribosomal P protein antibodies (anti-P) and anti-cardiolipin antibodies (aCL) were measured in serum and CSF by immunoassays. Analyses of white blood cell differential count, CSF-albumin/serum-albumin ratio, IgG-index in CSF and isoelectric focusing in serum and CSF were also performed. CSF specimens from 23 healthy individuals were used as controls. IFN-alpha was elevated in the CSF of 5 of 28 NPSLE patients compared to three of 14 among the non-NPSLE patients. IL-6 was elevated in CSF in three of 26 NPSLE patients. Normal concentration of IL-10 was found in CSF in all 27 NPSLE-patients analysed. IFN-alpha in serum was elevated in 18 of 28 NPSLE patients. No distinct clinical phenotype was related to elevated cytokine concentration in serum or CSF. One patient with cerebral involvement complicated by progressive multifocal leukoencephalopathy displayed a very high IFN-alpha concentration in serum. High concentration of TCC was present in CSF from only one patient with systemic vasculitis and focal cerebral symptoms. In conclusion, the results of this study suggest that the diagnostic value of serum and CSF concentrations of IFN-alpha, IL-10, IL-6 and TCC is limited in unselected neuropsychiatric SLE, probably due to the heterogeneity of NPSLE pathogenesis.