Association of IgG anti-brain antibodies with central nervous system dysfunction in systemic lupus erythematosus.

Sera from 20 patients with systemic lupus erythematosus (SLE) and active central nervous system (CNS) dysfunction were examined by indirect immunofluorescence for antibodies to neuronal membrane determinants. Warm-reactive IgG antibodies were demonstrable in 82% (9/11) of patients with clinical evidence for seizures or diffuse CNS disease, but these antibodies generally were absent in non-CNS SLE sera or when focal neurologic deficit or psychosis was the primary CNS manifestation. Cold-reactive antibodies of the IgM class were equally prevalent in patients with or without CNS disease and appeared to be more directly correlated with extra-CNS systemic illness. Absorption experiments with lymphocytes, brain homogenate, and various other tissues suggested a predominant brain-specificity for IgG antibodies and partial lymphocyte cross-reactivity for IgM antibodies. Interpretations of this special association between IgG anti-brain antibodies and diffuse CNS dysfunction in SLE are discussed.