Fluctuation of anti-Ro/SS-A antibody levels in patients with systemic lupus erythematosus and Sjögren's syndrome: A prospective study

S. Praprotnik, B. Bozic, T. Kveder, B. Rozman

Department of Rheumatology, University Medical Centre, Ljubljana, Slovenia.


Abstract
Objective
To determine whether the titers of anti-Ro/SS-A (Ro) antibodies fluctuate during the course of SLE and Sjögren's syndrome (SS) in parallel with disease activity, and if such fluctuations could be used to predict disease flares. We also evaluated whether the anti-Ro profile (anti-Ro 52, anti-Ro 60) changes over time, since such information could provide new insights into the induction and regulation of anti-Ro autoimmunity.

Methods
Sixteen patients with SLE and 15 patients with SS, all anti-Ro/SS-A antibody positive, were followed up for two years at three-month intervals. Clinical and laboratory parameters of disease activity were examined. Determination of the anti-Ro/SS-A titer was performed by counterimmunoelectrophoresis and the fine anti-Ro antibody specificity was determined by immunoblotting.

Results
The titers of anti-Ro antibodies fluctuated during the course of the illness in both SLE and SS patients. In SLE patients these changes were not (except in one case) associated with disease activity nor were they predictive of disease flares. The same was true for the SS patients, with the exception of two patients with skin vasculitis in whom anti-Ro antibody titers fluctuated in parallel with the disease activity. The anti-Ro antibody (anti-Ro 60 kD, anti-Ro 52 kD) specificity did not change in any of the patients during the follow-up period.

Conclusion
Anti-Ro antibodies could represent a valuable indicator of disease activity in SS patients with cutaneous disorders. They do not, on the other hand, reflect disease activity in patients with SLE. The stable antibody profile in both SLE and SS patients supports the hypothesis that autoantibody production is predominantly genetically regulated.

Key words
Systemic lupus erythematosus, Sjögren's syndrome, Ro/SS-A antibodies, prospective study.

S. Praprotnik, MS; B. Bozic, Associate Professor; T. Kveder, PhD; B. Rozman, Professor.

This study was supported by the Ministry of Science and Technology of Slovenia (Grant no. J3-7924-312).

Please address correspondence and reprint requests to: Sonja Praprotnik, M.S., University Medical Centre, Department of Rheumatology, Vodnikova 62, SI-1107 Ljubljana, Slovenia.

Received on June 1, 1998; accepted in revised form on August 31, 1998.

Clinical and Experimental Rheumatology 1999; 17: 63-68.
© Copyright Clinical and Experimental Rheumatology 1999.