This study shows that the susceptibility to Graves' disease is inherited associated with HLA and that whereas the disease susceptibility gene for Graves' disease is in linkage disequilibrium with HLA-B8 in Caucasians, it can be randomly associated with other HLA-B antigens.
The present report identifies an important immunogenic region of the TSH receptor and determinants on the TSH receptor for the two types of autoantibodies seen in hyperthyroid Graves' disease and hypothyroid idiopathic myxedema, TSAbs and TSBAbs, respectively.
Thyrotropin (TSH) and IgG preparations from patients with Graves' disease increase inositol phosphate as well as cAMP formation in Cos-7 cells transfected with rat TSH receptor cDNA.
We conclude that there are no major abnormalities in the structure of the TSH receptor gene in patients with Graves' disease, thyroid carcinoma, or subacute thyroiditis, although there may be a possibility of point mutations, small insertions, or deletions that cannot be detected by RFLP studies, and that there are large insertions or deletions in the region, including the TSH receptor gene, in some patients with thyroid adenoma.
This observation suggests a synergic involvement of a HLA class II allele (DPB1*0501) and an HLA class I allele (HLA-A2) in the pathogenesis of Graves' disease.
Among the 35 DR 3/4 positive subjects, 23 were diabetic (65.7%), two were healthy donors (5.7%), 10 had other diseases (28.5%) such as recurrent abortion (n = 3), hepatoma (n = 2), Graves' disease (n = 1), idiopathic hypoparathyroidism (n = 1), IgA nephropathy (n = 1), uveitis (n = 1) and gout (n = 1).
It has become evident in recent years that autoimmune thyroglobulin (Tg) antibodies of Graves disease and Hashimoto's thyroiditis show a restricted epitope repertoire compared to Tg heteroantibodies.
A cloned 3.088 kb cDNA coding for the entire mature human TPO was isolated from a cDNA library derived from a pathological thyroid gland of a Graves' disease patient and used further to generate a so-called TPO epitope cDNA library in order to map linear autoantigenic epitopes involving a recombinant molecular biology approach.
A portion of the unique area of the h-TSH receptor (approximately nucleotides 1100-1230) was directly sequenced in thyroid glands from patients with Graves' disease, multinodular goiter, and differentiated thyroid cancer.
The results imply that the correct folding and/or post-translational modifications of the polypeptide chain which are not achieved in recombinant proteins produced in Escherichia coli may be important for the binding of the hormone or Graves' disease autoantibodies to the TSH-R.
But no stimulating activity was observed in this IgG when CHO-K1 cells transfected with TSH-R cDNA were used, suggesting a possible existence of TSH-R non-mediated thyroid stimulating immunoglobulin in some cases of Graves' disease.