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Advances in detection of anti-dsDNA antibodies
Manole Cojocaru
Abstract: In clinical practice, antibodies to double-stranded deoxyribonucleic acid (dsDNA) are among the commonly used antinuclear (ANA) antibodies. The serological correlation between dsDNA and clinical outcome is an area of controversy. The dsDNA continue to show a high disease correlation with patients suffering from SLE, and it is possible that they play a role in its pathogenesis. Additionally, they have also been used clinically to monitor disease activity. Antibodies to DNA can be divided into 2 groups: those that react to denatured or single-stranded DNA (ssDNA) and those recognizing double-stranded DNA (dsDNA). Tests for anti-ssDNA antibodies have limited usefulness. In contrast, anti-dsDNA antibodies are relatively specific (95%) for SLE, making them useful for diagnosis. A negative test does not rule out the disease. Numerous methods have been devised to detect anti-dsDNA antibodies: indirect immunofluorescence, immunoenzymatic assay, counter immunoelectrophoresis, immuno- and western blotting. An immunofluorescent assay (IFA) is now available for the detection of anti-dsDNA antibodies in human serum. This IFA anti-dsDNA test kit uses Crithidia luciliae as a substrate. The optimally shaped Crithidia luciliae provide easy identification of the kinetoplast which contains dsDNA. The use a positive control not only validates the test but helps in the identification of the kinetoplast. Positive specimens are titred to an end-point determined as the last dilution to show kinetoplast fluorescence. A poor prognostic sign in SLE is the presence of anti-dsDNA antibodies indicating an increased likelihool of major organ involvement (e.g., renal disease or vasculitis). About 65% of SLE patients with active disease have anti-dsDNA antibodies but less than 5% have elevated levels when disease is quiescent. More than 80% of patients with lupus nephritis have elevated levels
Keywords: anti-dsDNA antibodies,SLE,disease activity,laboratory tests
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