Cerebrospinal fluid immunoglobulin abnormalities in systemic lupus erythematosus.

Central nervous system (CNS) involvement is a common and important complication in systemic lupus erythematosus. The mechanisms for CNS involvement are poorly understood and reliable diagnostic procedures are lacking. Pairs of serum and cerebrospinal fluid (CSF) specimens from 17 patients with clinical and serological manifestations of systemic lupus erythematosus were analysed. All 11 patients with definite or suspect clinical CNS disorder revealed some kind of abnormality in the CSF, in contrast to three of seven systemic lupus erythematosus patients without CNS disorder. The most prominent findings in systemic lupus erythematosus patients with CNS disorder were immune aberrations with oligoclonal bands on agarose isoelectric focusing (AIF) and elevation of IgG and IgM index, probably reflecting intrathecal production of IgG and IgM respectively. Intrathecal production of antiviral antibodies was found in four of 12 patients by AIF followed by immunofixation and subsequent autoradiography. An enzyme-linked immunoabsorbent assay (ELISA) could not detect autoantibodies against structural brain antigens.