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Anti-threonyl-tRNA synthetase, a second myositis-related autoantibody.

1984; Rockefeller University Press; Volume: 160; Issue: 2 Linguagem: Inglês

10.1084/jem.160.2.420

1540-9538

Michael B. Mathews, Morris Reichlin, Graham R.V. Hughes, Robert M. Bernstein,

Immunodeficiency and Autoimmune Disorders

An autoantibody known as PL-7 was found in the serum of four patients with myositis and one with a systemic lupus erythematosus-like syndrome. The PL-7 antigen is an 80,000 dalton polypeptide that coprecipitates with transfer RNA. In aminoacylation reactions, PL-7 IgG inhibited the charging of tRNA with threonine but had little or no effect on charging with other amino acids. Experimental antibodies raised against purified threonyl-tRNA synthetase recognized the same 80,000 dalton polypeptide, but tRNA was not coprecipitated. We conclude that PL-7 antibody is directed at threonyl-tRNA synthetase, and that different antigenic sites are recognized by the human and experimental autoantibodies. Our findings emphasize the link between myositis and autoimmunity to tRNA-related structures.