THE PREDICTIVE VALUE OF FLUCTUATIONS IN IGM AND IGG CLASS ANTI-DSDNA ANTIBODIES FOR RELAPSES IN SYSTEMIC LUPUS-ERYTHEMATOSUS - A PROSPECTIVE LONG-TERM OBSERVATION

Objective-This study investigated the predictive value of rises in IgM class antibodies against double stranded DNA (anti-dsDNA) for ensuing relapses in systemic lupus erythematosus (SLE) in comparison with ris es in IgG class antibodies. In addition, it was analysed whether rises in IgM class anti-dsDNA were associated with specific clinical manife stations of SLE. Methods-Thirty four of a cohort of 72 SLE patients wh o were positive for IgM class anti-dsDNA at the start of the study or at the time of a relapse were analysed monthly for class specific anti -dsDNA levels during a median observation period of 19.6 months. Disea se activity was scored according to the SLE Disease Activity Index, An ti-dsDNA were measured by IgM and IgG class enzyme linked immunosorben t assay (ELISA) and by Parr assay. Results-During the study 18 of 34 p atients experienced 26 relapses. Twenty two (85%) of the relapses were accompanied by a positive test for IgM class anti-dsDNA by ELISA, 23 (89%) were positive for IgG class anti-dsDNA by ELISA, and 25 (96%) we re positive by Farr Patients with rises in IBG class dsDNA by ELISA or in anti-dsDNA by Parr assay had a significantly higher cumulative ris k for relapses than patients without those increases (p=0.04 and p=0.0 3, respectively). This was not the case for rises in IgM class anti-ds DNA (p=0.16). Moreover, a rise in IgM class anti-dsDNA before a relaps e was not associated, expressed in terms of odds ratios, with specific clinical manifestations of SLE. Conclusion-Relapses of SLE are freque ntly accompanied by IgM class anti-dsDNA. Rises of IgM class anti-dsDN A, in contrast with rises in IgG class anti-dsDNA, are not a sensitive tool for predicting a relapse and are not associated with specific cl inical manifestations of SLE.