Abstract
Background: Previously, the presence of autoantibodies against type 2 deiodinase cys- and hom-peptides was investigated in Graves’ disease with relation to thyroid function, ophthalmopathy and therapy. The new design was to reveal the relationship among antithyroid antibodies involved in hormone synthesis.
Aim and scope: To demonstrate some regularity between the appearance of peptide autoantibodies and antithyroid antibodies against TSH receptor, thyroid peroxidase and thyroglobulin, the study followed the main path of hormone synthesis and the effect of antithyroid drug treatment. Has any effect of peptide autoantibodies on the titers of other autoantibodies?
Methods: The methods were described in our previous papers detailed. Autoantibodies against type 2 deiodinase peptides were detected with enzyme-linked immunosorbent assay in 78 patients with Graves’ disease and 30 controls. Thyroid hormones (TSH, FT4 and FT3) and antibodies against TSH receptor, thyroid peroxidase and thyroglobulin were measured with chemiluminescence immunoassay.
Results: The frequency of cys-peptide antibodies was greater in the new onset of Graves’ disease. Propylthiouracil treatment was associated with increased occurrence of cys-peptide antibodies (p<0.0069). No dose-dependency in methimazole treatment could be demonstrated for cys-peptide antibody levels. Antibodies against hom-peptide or both peptides demonstrated a strong relationship with the appearance of antithyroid antibodies. No peptide antibodies were associated with anti-thyroglobulin antibody positivity (0 cases out of 11 for hom-peptide, p<0.0071 and 0 cases out of 8 for both peptides, p<0.0251). In contrast, all cases with TSH receptor antibody positivity were positive for peptide antibodies (all cases out of 13 for hom-peptide, p<0.0139 and all cases out of 9 for both peptides, p<0.0470). TSH receptor antibody levels were relevantly decreased, when hom-peptide antibodies were present [24.35(15.68-37.8) vs 11.8(8.16-17.07) IU/l, p<0.0437].
Conclusion: The presence of hom-peptide antibodies was connected to the absence of antibodies against thyroglobulin and smaller anti-thyroid peroxidase antibody positivity. The presence and the high titers of TSH receptor antibodies demonstrated a close relationship with the appearance of hom-peptide antibodies. The relationship among the studied autoantibodies may depend on the alteration of thyroid hormone synthesis and the steric hindrance of targets and antithyroid drug treatment. Autoantibodies against type 2 deiodinase peptides can influence the therapeutical effectiveness.