Immunology and AllergyTier 2Topic

Laboratory investigations - double-stranded DNA (dsDNA) antibodies

What it is

Anti-dsDNA antibody - targets double-stranded DNA - a highly specific marker for SLE and one of the few autoantibodies whose titre is used to track disease activity over time
Present in ~60-70% of SLE patients; higher specificity for SLE than ANA, though lower sensitivity

Pathogenicity

Directly pathogenic in a subset of patients - anti-dsDNA/DNA immune complexes deposit in tissue (classically the glomerular basement membrane), fixing complement and driving lupus nephritis

Interpretation

Titre correlates with disease activity in many (not all) patients, particularly renal disease activity - rising titre with falling complement (C3/C4) is a classic pattern preceding a lupus flare
Measured by ELISA or the more specific (but less sensitive) Crithidia luciliae immunofluorescence assay

Monitoring

Serial monitoring of anti-dsDNA titre alongside complement levels is used to anticipate flares and guide treatment intensity in known SLE, distinguishing it from most other autoantibodies, which are not useful for monitoring
Rising titre with falling complement in a patient with known SLE should prompt closer clinical and renal monitoring, even before overt flare symptoms develop

Associations

Lupus nephritis, SLE disease activity monitoring, complement consumption (low C3/C4)

Limitation

Not every patient's anti-dsDNA titre tracks with disease activity - some patients run persistently high or persistently low titres regardless of clinical state, so trend must be interpreted per-patient rather than against a fixed threshold

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