How reliable are the new myositis-specific antibody kits?

The diagnosis of inflammatory myopathy is most often based on the positivity of autoantibodies in the bloodstream. Clinicians have diagnostic kits for this purpose but their reliability and interpretation thresholds are sometimes questionable. A team of immunologists from Toulouse (France) investigated:

  • the results of 270 patients tested positive for one of the two immunodots developed by the firm D-Tek (“myositis” kit and “synthetase” kit) were examined,
  • 128 corresponded to genuine myositis and 142 to other systemic pathologies,
  • the authors confirm the lack of specificity of these kits and propose to review the positivity thresholds, particularly for anti-SRP, anti-NXP2 and anti-MDA5 antibodies.


Myositis-specific autoantibodies in clinical practice: Improving the performance of the immunodot. Bories E, Fortenfant F, Pugnet G el al. Semin Arthritis Rheum. 2022 (Mars).55:151998.