[Clinical significance of antiribosomal antibodies. Study Group on Autoimmunity (GEAI)]

Autoantibodies directed against the ribosomal P proteins, P0, P1 and P2 (anti-P), have been related to lupus-related psychosis and/or depression. The diagnostic value of antibodies directed against other ribosomal proteins or 28S RNA (anti-no-P) remains unknown. A multicenter study including ten centers belonging to the study group for autoimmune diseases (GEAI) was conducted in order to determine the diagnostic value of anti-P and anti-no-P antibodies in a large population of patients.

The patients were selected on the basis of the presence of serum anti-ribosomal antibodies detected by indirect immunofluorescence (IF) on rat liver/kidney/stomach/pancreas sections and human HEp2 cells. The clinical course of all patients was studied using a predetermined survey. The specificity of anti-P antibodies were determined by Western blot.

Anti-ribosomal antibodies were found in 82 patients. Fifty-five of them had systemic lupus erythematosus and 27 had another disease. Only 54% of the anti-ribosomal antibodies detected by IF were anti-P and were found in 69% of the patients with systemic lupus erythematosus. Anti-no-P antibodies (46%) were preferably detected in patients who suffered from another disease (78%). In patients with systemic lupus erythematosus, neurological and psychiatric disorders were more frequent in the no-P group (47% vs. 16%, P < 0.01) than arthritis, which was found more frequently in the P group (78% vs. 53%, P < 0.05).

Anti P antibodies do not constitute a specific diagnostic marker of systemic lupus erythematosus, and lupus-related neuropsychiatric disorders would be preferably associated with the presence of anti no-P antibodies.