Background Autoantibody (Ab) detection including anti-nuclear Ab (ANA) plus anti-dsDNA/Chromatin Ab and/or anti-Sm Ab is central in the diagnosis and prognosis of systemic lupus erythematosus (SLE) and several methods can be used to detect them.
Objectives Our objective was to compare diagnostic accuracy for several anti-dsDNA Ab, anti-chromatin Ab and anti-Sm Ab detection.
Methods Accordingly, we compared different methods for anti-dsDNA Ab [indirect immunofluorescence using Crithidia Luciliae (CLIFT), anti-dsDNA by ELISA, anti-dsDNA by chemiluminescence (CLIA; IDS-ISYS, IDS) and anti-chromatin Ab (dsDNA-NCX, Euroimmun)] and anti-Sm Ab by ELISA (Immuno concept) and by CLIA (IDS-ISYS, IDS)]. The evaluation was performed in 49 SLE and 98 autoimmune disease controls including rheumatoid arthritis, scleroderma, vasculitis and Sjögren's syndrome.
Results In SLE patients, Ab sensitivity (and specificity) was 97.9% for AAN, 61.2% (92.9%) for anti-chromatin Ab, 36.7% (93 9%) for anti-dsDNA Ab by CLIA, 32.6% (95.9%) for anti-dsDNA Ab by ELISA, and 30.6% (100%) by CLIFT. For anti-Sm Ab, CLIA improved its detection (sensibility 18.4% versus 8.2% by ELISA; specificity 100% both). The best associations were found for anti-chromatin Ab and CLIFT (sensitivity 67.3% and specificity 91.8%), and for anti-chromatin and anti-Sm Abs by CLIA (sensitivity 53.1% and specificity 95.2%). Several associations were identified, including, for anti-chromatin Ab, articular [Odds ratio (OR)=28,41; p=0,002] and cardio vascular disease [OR=9,47; p=0,032], plus leucopenia [OR=13,72; p=0,049]; and for anti-Sm Ab by CLIA lupus glomerulonephritis [OR =5.0, p=0.05], and pleuropulmonary manifestations [OR =25.3; p=0.004].
Conclusions Combining anti-chromatin Ab detection by ELISA and anti-Sm Ab detection by CLIA contribute to improve the diagnosis and the prognosis of SLE.
Disclosure of Interest None declared