## Anti-dsDNA Antibodies in SLE **Key Point:** Anti-dsDNA antibodies are the most specific autoantibodies for SLE, present in 60–70% of SLE patients, and their presence is part of the SLE classification criteria. ### Immunofluorescence Pattern Anti-dsDNA antibodies produce a **homogeneous (diffuse) pattern** on indirect immunofluorescence (IIF) of HEp-2 cells, which is characteristic and helps distinguish SLE from other autoimmune conditions. ### Clinical Significance | Feature | Anti-dsDNA | Anti-histone | Anti-Ro/SSA | Anti-centromere | |---------|-----------|-------------|-----------|----------------| | **Specificity for SLE** | Very high (95%) | Low (seen in drug-induced LE) | Moderate (SLE, Sjögren's) | Low (limited sclerosis) | | **IIF Pattern** | Homogeneous | Speckled | Homogeneous/speckled | Centromeric | | **Disease Activity** | Correlates with active lupus nephritis | Not disease-specific | Neonatal lupus risk | Rare in SLE | | **Prevalence in SLE** | 60–70% | 40–50% | 40–60% | 1–2% | **High-Yield:** Anti-dsDNA antibodies correlate with lupus nephritis activity and are used to monitor disease progression. Rising titers often precede clinical flares. **Clinical Pearl:** The combination of anti-dsDNA + low complement (C3, C4) is highly predictive of active lupus nephritis and warrants aggressive immunosuppression.
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