Different Cytokine mRNA Profiles in Graves' Disease,Hashimoto's Thyroiditis,and Nonautoimmune Thyroid Disorders Determined by Quantitative Reverse Transcriptase Polymerase Chain Reaction (RT-PCR)

Intrathyroidal lymphocytes are a source of cytokines thought to stimulate or maintain the immune process within the thyroid in Graves' disease (GD) and Hashimoto's thyroiditis (HT). Quantitative assessment of the cytokine profile may provide important clues as to the Thl/Th2 balance prevailing in these diseases. We analyzed cytokine mRNA expression levels in thyroid tissue samples from 13 patients with GD, 2 with HT, 5 with nontoxic multinodular goiter (NTG), and 4 with thyroid autonomy (nodular = TA_nod and perinodular = TA_peri tissue) using multispecific competitor fragments with primer sequences for IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IFN-γ CD25, and CD3 δ-chain mRNA. Patients with GD were subdivided into two groups according to their serum levels of antibodies to thyroperoxidase (anti-TPO; GD_high > 4000 U/mL, GD_low ≤ 200 U/mL). These levels correlated positively with the CD3 δ-chain mRNA levels (r = 0.83) and with the T cell infiltration (r = 0.71) as determined by immunohistochemistry. Patients with GD_high demonstrated 2- to 4-fold higher IL-4 mRNA levels (as compared to all other investigated groups) and significantly higher IL-10 mRNA levels as compared to HT, GD_low, and TA_nod patients. Patients with GD_high also had significantly higher levels of IFN-γ, IL-1β, IL-8, and CD25 mRNA as compared to GD_low. The highest IFN-γ, IL-2, and CD25 mRNA levels were found in HT. The lowest mRNA levels of all the investigated groups were detected in TA_nod. No significant differences in IL-6 and IL-8 mRNA levels were found between most of the patient groups. In summary, patients with GD_high showed a shift to a more Th2-driven cytokine pattern. In contrast, the increase mRNA levels of Th1-related cytokines found in HT indicate predominantly cell-mediated cytotoxic processes.