The performance of different anti-dsDNA autoantibodies assays in Chinese systemic lupus erythematosus patients
BioPlex 2200 multiplexed assays system is an automatic method allowing detection of antinuclear antibodies (ANA). The aim of our study was to evaluate the determination of 13 autoantibodies against chromatinic and nonchromatinic nuclear antigens by the BioPlex 2200 system and to compare the results achieved by this method to those obtained with our routinely used immunoassays. One thousand and four serum samples consecutively sent for ANA detection were routinely tested by indirect immunofluorescence (IIF) on HEp2 cells. Among them, 321 were also analyzed by dsDNA enzyme immunoassay (EliA) test and 657 by double immunodiffusion (DID) for extractable nuclear antigen (ENA) antibodies. All the sera were evaluated by the BioPlex 2200 ANA screen kit allowing simultaneous detection of antibodies against the following antigens: dsDNA, chromatin, SSA-52 kDa, SSA-60 kDa, SSB, Sm, Sm/RNP, RNP-A, RNP-68 kDa, Scl70, centromere B, Jo-1, and P ribosomal proteins. The kappa coefficient between BioPlex 2200 and routine tests for detection of ANA on HEp2 cells, anti-dsDNA, and anti-ENA antibodies was, respectively, 0.31, 0.66, and 0.61. The comparison with our routine tests showed numerous discrepancies between IIF ANA screening and BioPlex but a good concordance for detection of anti-dsDNA and anti-ENA specificities. BioPlex 2200 system is a rapid and sensitive method for simultaneous quantitative detection of several autoantibodies. It is perfectly well adapted to determine ANA antigenic specificities of samples found positive using initial IIF screening. The capability of this multiplexed technology to analyze simultaneously 13 ANA autoantibodies leads to the rapid availability of an "autoimmune connective tissue disease serologic profile."