Which antibody is associated with activity or progression of SLE?

• A. Anti-Smith antibodies
• B. ANA
• C. Anti-RNP
• D. dsDNA antibodies

Answer: (D)

In systemic lupus erythematosus, what mirrors disease activity are the anti–double-stranded DNA antibodies. These antibodies bind to dsDNA and form immune complexes that deposit in organs, especially the kidneys, triggering complement activation and inflammation. As flares occur, anti-dsDNA titers often rise and complement levels (like C3 and C4) fall; when the disease calms, the titers typically decrease. This makes anti-dsDNA a useful marker for monitoring activity and progression.

Other antibodies have different roles. Anti-Smith antibodies are highly specific for SLE but don’t reliably track activity levels. ANA is very sensitive and can be present in many conditions, so it’s not useful for gauging activity. Anti-RNP antibodies are more associated with overlapping connective tissue diseases rather than the activity of SLE itself.