To develop a cell-ELISA method to detect antineuronal antibodies (anti-Ns) and evaluate the diagnostic value of anti-Ns in central nervous system involvement in systemic lupus erythematosus (CNS-SLE).
Anti-N was assessed in both serum and cerebrospinal fluid (CSF) samples from 38 patients with CNS-SLE, 29 with SLE without CNS involvement (non-CNS-SLE), 36 with other rheumatic diseases and 59 with non-rheumatic diseases with the CNS manifestations using a cell-ELISA method with 1% paraformaldehyde-fixed SK-N-MC neuroblastoma cells as substrate. Serum samples from 37 healthy donors were also included in this study. Patients with CNS-SLE who were anti-N positive in CSF were studied serially for CSF anti-N levels at times of treatment-associated improvement in CNS symptoms.
Serum anti-N levels were significantly increased in patients with SLE compared with other groups, with a sensitivity of 61.2% (41/67) and a specificity of 91.8% (p<0.001). CSF anti-N levels were significantly increased in patients with CNS-SLE, with a sensitivity of 47.4% (18/38) and a specificity of 89.7%, whereas only 10.3% (3/29) of patients with non-CNS-SLE had increased anti-N in CSF (p<0.001). CSF anti-N levels decreased significantly after effective treatment of CNS-SLE (p<0.05).
Serum anti-N is relatively specific to SLE. CSF anti-N is a sensitive and relatively specific antibody in diagnosing CNS-SLE and correlates with CNS-SLE activity.