Abstract
The antinuclear antibody (ANA) test is clinically useful for the diagnosis of connective tissue diseases (CTDs). However, it is widely recognized that positive ANA results are often observed in patients without CTD. Therefore, additional tests for specific autoantibodies are required for ANA-positive patients. Recently, the multiplex immunoassay test using the BioPlex 2200 ANA screen has enabled the simultaneous detection of 13 autoantibodies using a single serum sample. Therefore, in this study, we assessed the utility of the BioPlex assay in comparison with the conventional immunofluorescence (IF) and enzyme-linked immunosorbent assay (ELISA). Sera from 291 patients with CTD were analyzed for ANA and autoantibodies using the BioPlex assay, IF, and ELISA. The positive, negative, and total concordance rates between the BioPlex assay and IF were 89.6%, 64.3%, and 81.1%, respectively, whereas those between the BioPlex assay and ELISA were 94.7%, 85.7%, and 92.1%, respectively. The ANA-positive ratio obtained using the BioPlex assay was mostly higher than that obtained using IF and equivalent to that obtained by ELISA. The positive ratios of 8 specific autoantibodies obtained using the BioPlex assay were similar to the reported prevalence. Out of the 156 samples from patients without systemic lupus erythematosus (SLE), only 8 were positive for anti-dsDNA antibodies (5.1%). The BioPlex assay is an informative and convenient tool for the diagnosis of CTD.
