Anti-thyroglobulin antibody

Anti-thyroglobulin antibody (ATG), English name anti-thyroglobulin antibodies, was discovered by Roitt et al. In 1958 during serological research on autoimmune thyroiditis (Hashimoto's thyroiditis, etc.). ATG's target antigen, thyroglobulin (TG), is a soluble iodinated glycoprotein synthesized and secreted by thyroid epithelial cells. It has a molecular weight of 660 kD and consists of 2748 amino acids. It is a biosynthetic precursor of T3 (triiodothyronine) and T4 (tet-raiodothyronine, thyroxine, thyroxine). It is mainly stored in colloidal form in thyroid filters. In the vacuole cavity, the content of normal human serum is extremely small (10-40 ng / ml). Witebsky et al. Immunized rabbits with the same type of thyroid tissue and induced ATG and rabbit thyroiditis similar to human Hashimoto's thyroiditis. ATG is the most typical organ-specific antibody of various autoantibodies in humans. It is mainly IgG, with IgA accounting for 20% and IgM accounting for 5%. Among the four subclasses of IgG with ATG activity, the proportion of IgG increased significantly, about 6 times its normal proportion (5%). ATG cannot bind complement, which may have something to do with the higher proportion of IgG 4 subclasses. It may be more important because the epitopes on thyroglobulin are far apart, and cross-linking cannot be formed between the antibody molecules that it binds The reason.