The dsDNA IgG test is a chemiluminescent immunoassay (CLIA), for use on IDS automated analyzers. It is used for the quantitative determination of the specific IgG antibodies directed in dsDNA in human samples of serum or plasma (EDTA).
The extractable nuclear anti-antigen (ENA) autoantibodies represent a large family of non-organ- and non-species-specific autoantibodies, whose detection is of great importance in laboratory diagnosis of systemic rheumatic autoimmune diseases. (1,2,3,4)
From the laboratory point of view, systemic autoimmune diseases are characterized by the presence of anti-nuclear antibodies (ANAs). ANA is the first autoantibody test ordered for patients with suspected systemic autoimmune disorders.
Significantly high-titer positivity for ANAs should be further investigated via testing for anti-ENA and anti-dsDNA autoantibodies.
The anti-DNA antibodies are a heterogeneous group of immunoglobulins with different degrees of specificity and avidity. They may act against double-helix DNA (dsDNA) as well as against single-helix DNA (ssDNA). The anti-dsDNA antibodies recognize epitopes located along the deoxyribose-phosphate backbone(7) and the binding site is comprised of about 6 nucleotides.(8)
The anti-ssDNA antibodies, instead, recognize single nucleotide regions; this occurs when the molecule is denatured or in any case partially unwound.(9) The anti-ssDNA antibodies have low avidity and scarce diagnostic value due to their high nonspecificity. The anti-dsDNA antibodies have high diagnostic value as autoantibody markers in patients with systemic lupus erythematosus (SLE) and for this reason they are included in the SLE classification criteria of the American College of Rheumatology.(10)
Their prevalence in SLE varies from 40 to 80% according to case study and assay method. Besides its diagnostic role, the anti-dsDNA assay can play an important role in monitoring SLE, especially in patients with lupus nephritis. This is closely associated with the pathogenetic role of the antibodies: exacerbation of SLE is preceded by a constant and progressive increase of the anti-dsDNA antibodies followed by a sharp decline at the moment of clinical recrudescence, which is justified by glomerular deposition of high-avidity DNA/anti-dsDNA immune complexes.(11) For this reason, this assay is widely used in diagnosis and monitoring of SLE.
- CA von Mühlen, EM Tan. Autoantibodies in the diagnosis of systemic rheumatic diseases. Sem Arthr Rheum 1995; 24: 323-58.
- RL Humbel. Auto-immunité, auto-anticorps et maladie. In : Humbel RL, ed. Autoanticorps et maladies autoimmunes, Paris, France : Edition Scientifiques Elsevier; 1997: 17-20.
- PN Hollingsworth, SC Pummer, RL Dawkins. Antinuclear antibodies. In : Peter JB, Shoenfeld Y, eds. Autoantibodies. Amsterdam, The Netherlands : Elsevier Science BV; 1996: 74-90.
- CA Slater, RB Davis, RH Shmerling. Antinuclear antibodies testing. A study of clinical utility. Arch Int Med 1996; 156: 1421-5.
- RL Humbel. Detection of antinuclear antibodies by immunofluorescence. In : van Venrooij, Maini RN eds. Manual of Biological Markers of Disease. Dordrecht, The Netherlands : Kluwer; 1993: A2:1-16.
- National Committee for Clinical Laboratory Standardization. Quality assurance for the indirect immunofluorescence test for autoantibodies to nuclear antigen ( IF-ANA ). Approved Guideline. Wayne, PA: NCCLS I/LA2-A, vol. 16 ( 11 ); 1996.
- RJT Smeenk. Detection of antibodies to dsDNA : current insights into its relevance. Clin Exp Rheumatol 2002; 20: 294-300.
- DB Stollar, G Zon, RW Pastor. A recognition site on synthetic helical oligonucleotides for monoclonal anti-native DNA autoantibodies. Proc Natl Acad Sci USA 1986; 83: 4469-73.
- DS Pisetsky, CF Reich. The influence of DNA size on the binding of anti-DNA antibodies in the solid and fluid phase. Clin Immunol Immunopathol 1994; 72; 350-6.
- M Hochberg. Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum 1997; 40: 1725.
- AJG Swaak, R Smeenk. Detection of anti-dsDNA as a diagnostic tool: a prospective study in 441 non-systemic lupus erythematosus ( SLE ) patients with anti-dsDNA antibody ( anti-dsDNA ). Am Rheum Dis 1985; 44: 245-51.