Assay for myasthenia gravis

Abstract

A serum assay system for diagnosis of myasthenia gravis. The assay system includes a complex of acetylcholine receptor protein and a toxin labeled with a radioactive isotope. The complex is incubated with a serum sample from a patient. During incubation, antibodies engendered by myasthenia gravis bind to receptor sites in the complex. The resulting complex containing the antibodies is precipitated by addition of anti-immunoglobulin. Radioactivity in the resulting precipitate is measured and compared with a control.

What is claimed is: 
     
       1. A biochemical assay system comprising a complex of acetylcholine receptor protein derived from .[.human.]. .Iadd.mammalian .Iaddend.muscle with toxin labeled with a radioactive isotope. 
     
     
       2. A biochemical assay system in accordance with claim 1 wherein said toxin is derived from cobras and sea snakes. 
     
     
       3. A biochemical assay system in accordance with claim 1 wherein said toxin is from Naja naja siamensis or Bungarus multicinctus. 
     
     
       4. A biochemical assay .Iadd.system .Iaddend.in accordance with claim 1 wherein said radioactive isotope is I 125 . 
     
     
       5. A diagnostic test for determination of myasthenia gravis comprising the steps of preparing a complex of acetylcholine receptor protein derived from .[.human.]. .Iadd.mammalian .Iaddend.muscle, toxin and a radioactive isotope, incubating said complex with a serum sample from a patient so as to join antibodies engendered by myasthenia gravis to receptor in said complex, precipitating said antibody-complex with anti-immunoglobulin and measuring the radioactivity of said precipitate. 
     
     
       6. A diagnostic test in accordance with claim 5 wherein said toxins are derived from cobras and sea snakes. 
     
     
       7. A diagnostic test in accordance with claim 5 wherein said toxin is from Naja naja siamensis or Bungarus multicinctus. 
     
     
       8. A diagnostic test in accordance with claim 5 wherein said radioactive isotope is I 125 .