ANTI-TUBULIN ANTIBODIES IN AUTOIMMUNE THYROID-DISORDERS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 52  (2) , 325-332
Abstract
The presence of circulating antibodies directed against a cytoskeletal element, microtubules, in patients with autoimmune thyroid disorders, was studied using pure brain tubulin as antigen. Immune complexes were immunoprecipitated using a goat anti-human Ig antibody. Twenty sera among 48 (41%) from patients with Graves'' disease and 9 sera among 16 (56%) from patients with Hashimoto''s thyroiditis had increased levels of anti-tubulin antibodies compared to that of 26 sera from control subjects. Only 1 serum among 11 from patients with toxic adenoma was positive. Similar results were obtained using protein A adsorbent to collect immune complexes. Specificity of the tubulin binding activity was ascertained by dilution of the sera and displacement of tracer tubulin by unlabeled pure tubulin from rat or human brain. Anti-tubulin antibody titers were variable: one serum was positive at dilution higher than 1:15,000, a titer similar to those obtained in animals experimentally immunized against tubulin. Binding of labeled and unlabeled tubulin to Ig from positive sera was strictly competitive. The apparent affinity constant for the binding of tubulin to human anti-tubulin autoantibodies determined on 4 sera was 0.2-0.6 .times. 109/M. There was no significant association between anti-tubulin antibodies and anti-microsomal antibodies or anti-thyroglobulin antibodies or thyroid stimulating antibodies. Only 5-6% of sera from patients with other autoimmune diseases: lupus erythematosis or pernicious anemia, had increased levels of anti-tubulin antibodies. Tubulin represents a new autoantigen which is expressed rather specifically in autoimmune thyroid disorders and probably independently from the classical thyroid antigens.