Systemic lupus erythematosus (SLE) is characterised by the presence of antibodies to double-stranded DNA (dsDNA). These antibodies are supposedly involved in the pathogenesis of SLE. Eighty percent of patients develop a clinical relapse within 10 weeks after a significant rise in anti-dsDNA level. This can be prevented by the administration of corticosteroids at the time of rise in anti-dsDNA. We hypothesise that administration of mofetil mycophenolate (MMF) will have similar effects without the side effects of corticosteroids.

SLE patients (n = 36) were followed monthly for a rise in levels of anti-dsDNA, defined as exceeding 125% of the level of the previous sample, and amounting at least 15 E/ml within a 4-month period. At the time of a rise patients started with 2000 mg MMF daily for a period of 6 months. Patients were monitored monthly for the occurrence of a clinical relapse and to assess serological activity and state of activation of CD4+, CD8+ and CD19+ lymphocyte subsets.

In 10 patients a serological relapse was encountered. All patients started MMF and completed a 6 months study period without the occurrence of a clinical relapse. Side effects were minimal. Antibodies to dsDNA decreased during the study period (P < 0.001) associated with a decrease in activation of CD19+ lymphocytes. No difference in the state of activation of CD4+ or CD8+ lymphocyte subsets could be demonstrated.

Administration of MMF after a rise of antibodies to dsDNA prevents the occurrence of clinical relapses of SLE and is well tolerated.