A 35-year-old woman with lupus erythematosus has antibodies against double-stranded DNA and Smith antigen. Anti-dsDNA titers are useful for monitoring disease because:
- A They are diagnostic of lupus nephritis and their titers predict renal flares
- B Their titers correlate with disease activity (rise during flares) and they are highly specific for SLE ✓
- C They cause direct complement consumption and predict APS thrombosis
- D They cross-react with RNA polymerase and predict anti-Ro-negative neonatal lupus
Correct answer: B. Their titers correlate with disease activity (rise during flares) and they are highly specific for SLE
Explanation
Anti-dsDNA antibodies are highly specific (~97%) for SLE and their titers correlate well with disease activity — rising titers herald flares and falling titers reflect response to therapy. While anti-dsDNA (particularly anti-C1q) may contribute to lupus nephritis through immune complex deposition, the primary clinical utility of serial anti-dsDNA titers is monitoring disease activity. Anti-Smith antibodies are specific but do not fluctuate with activity. Antiphospholipid antibodies (not anti-dsDNA) predict APS thrombosis.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.