Anti dsDNA (IFA)
Sample: Serum
Schedule: Daily (Immunofluorescence)
Units: Titer
Range: Negative
Remarks: dsDNA antibodies are found mainly in SLE and are important for diagnosis of that condition as well as for monitoring the treatment. IgG antibodies to dsDNA are present in 60% of active SLE cases. They may be present in smaller fractions of patients with other Rheumatic Disorders and in Chronic Active Hepatitis, Infectious Mononucleosis, and Biliary Cirrhosis. In the past it was a rule of thumb that it was unnecessary to test for anti-DNA in patients with a negative test for Antinuclear antibodies (ANA Hep-2 cells).
A group of "ANA-negative" lupus patients has been described with Anti-ss-DNA and Anti-SS-A/Ro and Anti-SS-B/La. However, HEp-2 substrate is much more sensitive than frozen section substrates; and it is uncommon for Anti-SS-A/Ro to be negative with such substrates. Procainamide and hydralazine may induce Anti-ss-DNA antibodies and Anti Histone antibodies.
Following liters of anti-DNA antibody may be of use in evaluating response to therapy, but should be regarded as a guide rather than a rigid dictator of treatment. Titers correlate with activity of lupus nephritis, but ANA and anti-DNA antibodies are less reliably related to active progressive lupus glomerulonephritis than are Complement C3 and CH50 complement depression.
