| Autor: |
Fritzler MJ; Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada., Bentow C; Werfen Autoimmunity, San Diego, CA 92131, USA., Satoh M; Department of Human, Information and Science, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.; Department of Medicine, Kitakyushu Yahata-Higashi Hospital, Kitakyushu 805-0071, Japan., McHugh N; Department Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK., Ghirardello A; Unit of Rheumatology, Department of Medicine, University of Padova, 35122 Padua, Italy., Mahler M; Werfen Autoimmunity, San Diego, CA 92131, USA. |
| Abstrakt: |
(1) Background: Myositis specific antibodies (MSA) are important diagnostic biomarkers. Among the rarest and most challenging MSA are anti-OJ antibodies which are associated with anti-synthetase syndrome (ASS). In contrast to the other tRNA synthetases that are targets of ASS autoantibodies (e.g Jo-1, PL-7, PL-12, EJ, KS, Zo), OJ represents a macromolecular complex with several ribonucleoprotein subunits. Therefore, the choice of the antigen in autoantibody assays can be challenging. (2) Methods: We collected two independent cohorts with anti-OJ antibodies, one based on a commercial line immunoassay (LIA) (n = 39), the second based on protein immunoprecipitation (IP) (n = 15). Samples were tested using a particle-based multi-analyte technology (PMAT) system that allows for the simultaneous detection of antibodies to various autoantigens. For the detection of anti-OJ antibodies, two different antigens were deployed (KARS, IARS) on PMAT. The reactivity to the two antigens KARS and IARS was analyzed individually and combined in a score (sum of the median fluorescence intensities). (3) Results: In the cohort selection based on LIA, 3/39 (7.7%) samples were positive for anti-KARS and 7/39 (17.9%) for anti-IARS and 14/39 (35.9%) when the two antigens were combined. In contrast, in samples selected by IP the sensitivity of anti-KARS was higher: 6/15 (40.0%) samples were positive for anti-KARS, 4/15 (26.7%) for anti-IARS and 12/15 (80.0%) for the combination of the two antigens. 18/39 (46.2%) of the LIA samples generated a cytoplasmic IIF pattern (compatible with anti-synthetase antibodies), but there was no association with the antibody levels, neither with LIA nor with PMAT. (4) Conclusions: The combination of IARS and KARS might represent a promising approach for the detection of anti-OJ antibodies on a fully automated platform. |
