ABSTRACT
OBJECTIVE: Interleukin-33 (IL-33), a 30 kDa cytokine, is a member of IL-1 family. It is considered to be an autoimmune biomarker associated with T helper 2 (Th 2) response. γ-interferon is also produced by T helper 1 (Th 1) cells to induce cellular responses. γ-interferon is a 143-amino acid residue glycoprotein with several biological functions including potent anti-viral activity, stimulation of macrophage activity, modulation of Major Histocompatibilty Complex class I/class II expression, and regulation of a diversity of specific immune responses. The aim of this study was to investigate the serum levels of IL-33 and γ-interferon in different thyroid disorders. METHODS: Twenty patients with Graves' disease, 21 patients with Hashimoto hypothyroidism, 21 euthyroid Hashimoto patients, and 27 control subjects were recruited to this study. Blood samples were drawn and IL-33 and γ-interferon tests were analyzed from 89 participants. Serum IL-33 and γ-interferon analyses were performed by enzyme-linked immunosorbent assay. RESULTS: There was no statistically significant difference between groups for serum γ-interferon levels. Serum IL-33 concentrations were significantly higher in Graves' disease group compared to the other groups (p<0.000) There was a positive correlation between serum IL-33 and free triiodothyronine (fT3) and thyroxine (fT4). Also, negative correlation between serum IL-33 and thyroid-stimulating hormone (TSH) was statistically significant (p<0.000). CONCLUSIONS: The correlation of serum IL-33 with thyroid hormone levels may be a useful indicator for Graves' disease. These findings may help to make evident the pathophysiologic processes of the autoimmune thyroid diseases and improve therapeutic methods. .