Autoantibodies against complement C1q correlate with the thyroid function in patients with autoimmune thyroid disease.
Autoantibodies against complement C1q (anti-C1q) have been well described in patients with systemic lupus erythematosus, where they correlate with the occurrence of severe lupus nephritis. However, data on anti-C1q in organ-specific autoimmune diseases are scarce. In order to determine the prevalence of anti-C1q in patients with autoimmune thyroid disorders (AITD) and a possible association with thyroid function, we measured prospectively anti-C1q in 23 patients with Graves' disease (GD) and 52 patients with Hashimoto's thyroiditis (HT). Anti-C1q levels were correlated with parameters of thyroid function and autoantibodies against thyroperoxidase, thyroglobulin and thyroid stimulating hormone (TSH) receptor. Twenty-one patients with multi-nodular goitre and 72 normal blood donors served as controls. We found elevated concentrations of anti-C1q more frequently in patients with AITD than in controls: seven of 23 (30%) patients with GD and 11 of 52 (21%) patients with HT, compared with one of 21 (5%) patients with multi-nodular goitre and six of 72 (8%) normal controls. Anti-C1q levels did not correlate with thyroid autoantibodies. However, in GD absolute levels of anti-C1q correlated negatively with TSH and positively with free thyroxine (FT4) and triiodothyronine (FT3). In contrast, in HT, anti-C1q correlated positively with TSH levels. No correlation between TSH and thyroid autoantibodies was found. In conclusion, we found an increased prevalence of anti-C1q in patients with AITD and their levels correlated with the thyroid function in both GD and HT. This correlation seems to be independent of thyroid autoantibodies. Therefore, anti-C1q might point to a pathogenic mechanism involved in the development of AITD that is independent of classical thyroid autoantibodies.
Potlukova
E
E
3rd Clinic of Medicine, General Teaching Hospital and 1st Faculty of Medicine, Charles University, Prague, Czech Republic. eliska.potlukova@seznam.cz
Jiskra
J
J
Limanova
Z
Z
Kralikova
P
P
Smutek
D
D
Mareckova
H
H
Antosova
M
M
Trendelenburg
M
M
D000208:Acute Disease; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D015922:Complement C1q / Q000276:immunology*; D005260:Female; D006042:Goiter / Q000276:immunology; D006111:Graves Disease / Q000276:immunology* / Q000503:physiopathology; D050031:Hashimoto Disease / Q000276:immunology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000503:physiopathology
D001323:Autoantibodies; D015922:Complement C1q