Comparison of automated multiplexed bead-based ANA screening assay with ELISA for detecting five common anti-extractable nuclear antigens and anti-dsDNA in systemic rheumatic diseases

Background: A newly developed and totally automated Luminex-based assay, the BioPlex™ 2200 system, is able to detect various autoantibodies simultaneously from a single sample. We compared the BioPlex™ 2200 system with ELISA for the detection of six autoantibodies. Methods: A total of 127 serum samples from the patients with systemic rheumatic diseases were collected and assayed with the BioPlex™ 2200 system (Bio-Rad, USA) and conventional ELISA (INOVA Diagnostics, USA) for 5 anti-extractable nuclear antigens. Additionally, relative sensitivity of the BioPlex™ 2200 system for detecting anti-dsDNA was evaluated with 79 specimens from SLE patients, which were positive for anti-dsDNA by ELISA. Results: The concordance rates between ELISA and the BioPlex ranged from 88.1% for anti-RNP to 95.2% for anti-Scl-70, and the kappa coefficients between the results by the two assays were from 0.48 to 0.67. Among the 79 anti-dsDNA positive specimens by ELISA, seventy-eight (98.7%) showed positive results for anti-dsDNA by the BioPlex. Conclusions: The BioPlex™ 2200 system showed comparable results with those by conventional ELISA for detecting autoantibodies, and this automated assay could measure multifarious autoantibodies concurrently in a single sample. It could be effectively used in clinical laboratories for screening autoimmune diseases.