Jo-1 Antigen

The Jo-1 antigen is histidyl-transfer ribonucleic acid (t-RNA) synthetase. This enzyme is partially responsible for attaching t-RNA to their cognate rRNA (2). The Jo-1 antigen migrates as a 53 kD protein on SDS-PAGE. Anti-Jo-1 autoantibodies were originally described as precipitating autoantibodies in sera of patients with polymyositis. It was later realized that the anti-Jo-1 antibodies were specific for patients with polymyositis. The target for the anti-Jo-1 antibodies was one of a family of distinct cellular enzymes, the aminoacyl t-RNA synthetases (1). The presence of autoantibodies against the Jo-1 antigen has been reported in up to 23% of polymyositis patients by immunodiffusion (3). Anti-Jo-1 antibodies are almost completely specific for myositis, being more common in polymyositis than dermato-myositis(4), and rare in children (5). The presence of anti-Jo-1 antibodies defines a distinct group of polymyositis patients with interstitial disease, arthritis, and fevers (6). The anti-Jo-1 response appears to be self-antigen driven, having a broad spectrotype over time undergoing isotype switching. Anti-Jo-1 antibodies also inhibit the function of human histidyl tRNA synthetase more than they do from other species (6).

1. Targoff IN, Reichlin M. “Measurement of Antibody to Jo-1 by ELISA and Comparison to Enzyme Inhibitory.” An of Immun: Vol: 138, 1987, pg 2874-2882.
2. Hershey JWB. “The Translational Machinery: Components and Mechanism.”, Cell Biology, Vol: 4, 1980, pg 1-68.
3. Nishiki M and Reichlin M. “Heterogeneity of Precipitating Antibodies in Polymyositis and Dermatomyositis, Terization of the Jo-1 Antibody System.” Arthritis Rheum,1980, pg 881.
4. Reichlin M, Maddison PJ, Targoff IN, Bunch T, Arnett FC, Sharp GC, Treadwell E, and Tan EM. “Antibodies Nuclear/Nucleolar Antigen in Patients with Polymyositis Overlap Syndrome.” J Clin Immunol, 1984.
5. Pachman LM, Hardin JA, Cobb MA, and Arroyave CM. “The Antinuclear Antibody (ANA) in Juvenile Dermatomyositis (JDMS) is not Jo-1, Suggesting that JDMS and Polymyositis (PM) are Different Diseases.” Arthritis Rheum. , 1984.
6. Takeuchi K, Tan EM, Pollard KM. “Similarity of Epitopes of an Autoantigen Fibrillarin-Recognized by Human Immune Sera and Murine Autoimmune Models.” American College of Rheum, 56th Annual Scientific 0ct 11-15, 1992, Atlanta. Poster Presentations.