Jo-1 autoantibodies are also called histidyl-tRNA synthetase antibodies or polymyositis antibodies. They are an acknowledged marker for the disease polymyositis.
Testing for these autoantibodies is advisable when patients are demonstrating signs and symptoms compatible with connective tissue disease, such as muscle pain and limb weakness, Raynaud’s syndrome, arthritis, and concomitant pulmonary signs and symptoms.
The autoantigen responsible is the Jo-1 antigen, also called histidyl tRNA synthetase. The autoantigen is member of the amino acyl-tRNA synthetase family of enzymes and part of the ENA set. Histidyl tRNA synthetase is a cytoplasmic enzyme found in all nucleated cells. During protein biosynthesis histidyl tRNA synthetase catalyses the binding of the amino acid histidine to transfer RNA (tRNA). Jo-1 antibodies bind to conformational epitopes of the enzyme protein, inhibiting its catalytic activity.
Most commonly Jo-1 antibodies occur in myositis patients with interstitial lung disease. In patients with interstitial pulmonary fibrosis and symmetrical polyarthritis Jo-1 antibodies are detectable in up to 50% of cases.
Tests offered by ORGENTEC Diagnostika
Indirect Immunofluorescence Assay (IFA):