Development of enzyme-linked immunosorbent assays for the detection of myositis-specific autoantibodies against signal recognition particle, nuclear matrix protein 2, and small ubiquitin-like modifier activating enzyme.

OBJECTIVES

To develop and validate enzyme-linked immunosorbent assay (ELISA) systems for the detection of autoantibodies against the signal recognition particle (SRP), nuclear matrix protein 2 (NXP2), and small ubiquitin-like modifier activating enzyme (SAE).

METHODS

Serum samples from 288 individuals were analysed, including 183 patients with idiopathic inflammatory myopathies, 20 with other neuromuscular diseases, 35 with non-idiopathic inflammatory myopathies and other systemic autoimmune rheumatic diseases, and 50 healthy controls. ELISA systems were established using recombinant SRP, NXP2, and SAE proteins expressed in insect cells or Escherichia coli. The diagnostic performance of the ELISAs was assessed in comparison with the 'gold-standard' immunoprecipitation assays.

RESULTS

The ELISAs demonstrated high concordance with immunoprecipitation assays, with positive and negative percent agreements of 97.4% and 100% for anti-SRP, 100% and 99.6% for anti-NXP2, and 100% and 99.6% for anti-SAE antibodies, respectively.

CONCLUSIONS

The newly developed ELISA systems showed excellent agreement with immunoprecipitation assays, supporting their applicability for routine clinical use in detecting anti-SRP, anti-NXP2, and anti-SAE autoantibodies.