Right-positive and false-positive test results of anti-double-stranded DNA nucleosome-complexed enzyme-linked immunosorbent assay (Anti-dsDNA-NcX ELISA). (A) Scatterplot showing Anti-dsDNA-NcX ELISA immunoglobulin G results in 964 different sera. Dotted line represents the manufacturer's threshold (100 IU/ml). Values >800 IU/ml were set to 800 IU/ml for a clearer arrangement of the figure. SLE, systemic lupus erythematosus; SSc, systemic sclerosis; SS, Sjögren's syndrome; RA, rheumatoid arthritis; ND, normal donors; (B) Table showing all non-SLE patients who tested positive in the Anti-dsDNA-NcX ELISA listed with the test results of all measured assays and clinically relevant findings. Positive test results according to a comparable specificity of 98.9% are marked in bold. Nuc, anti-dsDNA-nucleosome ELISA; Farr, radioimmunoassay; CLIF, Crithidia luciliae immunofluorescence assay; ANA, antinuclear antibodies; C3, complement component 3.
Biesen et al. Arthritis Research & Therapy 2011 13:R26 doi:10.1186/ar3250