Sensitivity and specificity of anti‐Jo‐1 antibodies in autoimmune diseases with myositis

Objective. To determine the sensitivity and specificity of anti‐Jo‐1 in systemic sclerosis (SSc) patients with and without myositis. Methods. Immunoblots on HeLa nuclei were used to screen sera from 554 consecutive connective tissue disease patients. Those who had 45–55‐kd bands, all patients with polymyositis/dermatomyositis (PM/DM), and a random selection of SSc, Raynaud's disease, systemic lupus erythematosus, and rheumatoid arthritis patients were also studied by anti–Jo‐1 enzyme‐linked immunosorbent assay and by immunoblots on rabbit pooled aminoacyl‐transfer RNA synthetase. Results. Anti–Jo‐1 was present only in 8 of the 40 PM/DM patients. Conclusion. Anti–Jo‐1 is specific for PM/DM.