Objective: To compare the role of antibodies against the ribosomal P protein (anti-P) with that of antibodies against neuronal cells (anti-N) in the pathogenesis of central nervous system (CNS) involvement in systemic lupus erythematosus (SLE).
Methods: Sera from 87 SLE patients (27 with non-CNS SLE, 34 with lupus psychosis, and 26 with nonpsychotic CNS lupus) and from 20 control patients with neurologic manifestations without SLE and cerebrospinal fluid (CSF) from 41 patients with CNS lupus and from the 20 control patients were assayed for IgG anti-P and anti-N by an enzyme-linked immunosorbent assay (ELISA) using ribosomal P synthetic peptides and by a cell ELISA using paraformaldehyde-fixed SK-N-MC neuroblastoma cell lines, respectively.
Results: Serum anti-P levels were significantly elevated in patients with lupus psychosis compared with those with non-CNS SLE or those with nonpsychotic CNS lupus, whereas there were no significant differences in serum anti-N levels among these 3 groups. In contrast, CSF anti-N levels were significantly elevated in patients with lupus psychosis compared with those with nonpsychotic CNS lupus and compared with non-SLE controls, whereas CSF anti-P were not detected in most of the patients.
Conclusion: The results indicate that anti-P in the systemic circulation and anti-N in the CSF are involved in the development of lupus psychosis.