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

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.