Case 641 -- Antibodies to dsDNA
CASE 1: Systemic lupus erythematosus with lupus nephritis (WHO grade III-IV) and possibly autoimmune hepatitis.
CASE 2: Infliximab induced ANA and dsDNA production.
To summarize the two cases:
Both the patients have positive ANA and dsDA antibodies. However, the clinical presentation and the supporting laboratory findings are very different.
The overall picture is most concerning for SLE in the first patient but not so much in the second patient.
SLE is an autoimmune disease characterized by the production of auto antibodies binding to nuclear antigens. These include antinuclear antibodies, Anti-Sm antibodies, Anti- RNP antibodies, Anti-Ro, Anti- La, anti- cardiolipin, lupus anticoagulant, anti thyroglobulin, anti thyroid microsomes, anti-dsDNA. In addition it is usually associated with a decrease in complement (C3 and C4) levels, primarily when there are antibodies to dsDNA present and immuncomplex glomerulonephritis.
Approximately 60% of SLE patients have anti- dsDNA antibodies at some time during their illness when tested. 1, 2 . Antibodies to dsDNA are particularly important as their levels in the serum correlate with disease activity especially for renal pathogenecity.1 Pathogenic dsDNA antibodies have an IgG isotype, bind to both ss and dsDNA, have narrow crossreactivity and demonstrate high avidity for dsDNA.3 However, the antigen for anti-dsDNA has not been conclusively identified. 4 Most normal subjects have low affinity IgM antibodies to ss-DNA in their serum. Anti- dsDNA antibodies are an important diagnostic marker and pathogenic factor for systemic lupus erythematosus (SLE). Rise in IgM in contrast to rise in IgG class dsDNA (89%), are not sensitive tool for predicting a relapse5.
Over view of anti- DNA testing:
The DNA molecule has several unique features which have a direct bearing on its immune reactions and its laboratory diagnosis.
- The double-stranded (ds) conformation can undergo heat denaturation and upon fast cooling convert to the single stranded conformation and hence may pick antibodies to ss DNA, increasing the likelihood of obtaining a false positive result when testing for antibody to dsDNA
- It has a large surface area with repeating antigenic determinants (nucleotides and turns of the helix) which increasing the binding avidity of the antibodies.
- The polyanionic nature makes DNA bind to many serum proteins (complement and immunoglobulins) under physiological conditions and precautions have to be taken in order to exclude non-specific DNA binding in the assays. 6
This consists of distinct uniformly sized colour-coated microspheres (potentially 100 different sets) with each antigen conjugated to an individual set of microspheres. Each set of microspheres is classified on the basis of its unique orange and red fluorescence intensity which allows identification of the analyte being analysed. This enables simultaneous detection of nine or 10 autoantibodies specificities (dsDNA and extractable nuclear antigens) allowing an overview of antibody profile for each patient in a unique run with a unique calibration. However, it is important to make absolutely certain that there is no ssDNA present.
Induction of autoantibodies following infliximab therapy:
Induction of ANA and anti-dsDNA has been linked to administration of infliximab for various disease conditions including Rheumatoid arthritis, Psoriasis, Crohns' disease8-10.
- ANA and anti-dsDNA autoantibodies have been observed in 22% to 57% and in up to 33% of infliximab-treated patients, respectively.
- The time to induction of anti-dsDNA autoantibodies ranges from 1 to 12 months after the beginning of treatment mostly after the second or third infusion, although this was variable.
- No other organ-specific or nonorgan-specific autoantibodies are usually detected.
- Most of induced anti-dsDNA antibodies are of the IgM isotype or against ssDNA.
- Induction of autoantibodies (even the IgG type) do not seem to be predictive of the development of drug-induced lupus except in rare cases which resolved after discontinuation of therapy.
- Infliximab causes blockage of TNF- ? and disturbance of the cytokine network. It also may have selective proapoptotic effect on immune cells (T lymphocytes and monocytes). This could promote the release of numerous nuclear autoantigens, leading to the development of autoantibodies against nuclear compounds.
In case 1 ANA and anti-dsDNA truly represent systemic lupus erythematosus, however, in case 2 the induction of ANA and anti-dsDNA is most likely secondary to infliximab therapy. Although both patients had antibody to dsDNA, only 1 had clinical disease associated with the antibody. Thus, there are characteristics of the antibody, possibly related to its affinity for the epitope that it binds to on native DNA, that modulate its clinical effect. There is a temporal relationship with development of no new symptoms that could explain a new autoimmune disease like lupus in this patient. Also the patient improved objectively despite no steroids.
- er Borg EJ, Horst G, Hummel EJ, Limburg PC, Kallenberg CG. Measurement of increases in anti-double-stranded DNA antibody levels as a predictor of disease exacerbation in systemic lupus erythematosus. A long-term, prospective study. Arthritis Rheum 1990;33;634-643.
- Smeenk RJ, van den Brink HG, Brinkman K, Termaat RM, Berden JH, Swaak AJ. Anti-dsDNA: choice of assay in relation to clinical value. Rheumatol Int 1991;11;101-107.
- Winfield JB, Faiferman I, Koffler D. Avidity of anti-DNA antibodies in serum and IgG glomerular eluates from patients with systemic lupus erythematosus. Association of high avidity antinative DNA antibody with glomerulonephritis. J Clin Invest 1977;59;90-96.
- Zhang W, Reichlin M. A peptide DNA surrogate that binds and inhibits anti-dsDNA antibodies. Clin Immunol 2005;117;214-220.
- Bootsma H, Spronk PE, Ter Borg EJ et al. The predictive value of fluctuations in IgM and IgG class anti-dsDNA antibodies for relapses in systemic lupus erythematosus. A prospective long-term observation. Ann Rheum Dis 1997;56;661-666.
- Eilat D. Anti-DNA antibodies: problems in their study and interpretation. Clin Exp Immunol 1986;65;215-222.
- Hahn BH. Antibodies to DNA. N Engl J Med 1998;338;1359-1368.
- Nancey S, Blanvillain E, Parmentier B et al. Infliximab treatment does not induce organ-specific or nonorgan-specific autoantibodies other than antinuclear and anti-double-stranded DNA autoantibodies in Crohn's disease. Inflamm Bowel Dis 2005;11;986-991.
- Pink AE, Fonia A, Allen MH, Smith CH, Barker JN. Antinuclear antibodies associate with loss of response to antitumour necrosis factor-alpha therapy in psoriasis: a retrospective, observational study. Br J Dermatol 2009.
- Comby E, Tanaff P, Mariotte D, Costentin-Pignol V, Marcelli C, Ballet JJ. Evolution of antinuclear antibodies and clinical patterns in patients with active rheumatoid arthritis with longterm infliximab therapy. J Rheumatol 2006;33;24-30.
Contributed by Nidhi Aggarwal, MD and Bruce Rabin, MD, PhD