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 Th1/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 = TAnod and perinodular = TAperi tissue) using multispecific competitor fragments with primer sequences for IL-1 beta, IL-2, IL-4, IL-6, IL-8, IL-10, IFN-gamma, CD25, and CD3 delta-chain mRNA. Patients with GD were subdivided into two groups according to their serum levels of antibodies to thyroperoxidase (anti-TPO; GDhigh > 4000 U/mL, GDlow < or = 200 U/mL). These levels correlated positively with the CD3 delta-chain mRNA levels (r = 0.83) and with the T cell infiltration (r = 0.71) as determined by immunohistochemistry. Patients with GDhigh 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, GDlow, and TAnod patients. Patients with GDhigh also had significantly higher levels of IFN-gamma, IL-1 beta, IL-8, and CD25 mRNA as compared to GDlow. The highest IFN-gamma, IL-2, and CD25 mRNA levels were found in HT. The lowest mRNA levels of all the investigated groups were detected in TAnod. No significant differences in IL-6 and IL-8 mRNA levels were found between most of the patient groups. In summary, patients with GDhigh 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 T cell-mediated cytotoxic processes.

There has been much controversy about the presence of TNF‐α within thyroid tissue. We therefore conducted a study to determine if TNF‐α mRNA is present in thyroid tissue and thyroid‐derived cells. Semiquantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) was employed with a heterologous competitor fragment. Significantly lower levels of TNF‐α mRNA were found in the autonomous nodules from patients with thyroid autonomy (TA; n = 4; 5.7 ± 1.3 arbitrary units (AU) (mean ± s.e.m.); P < 0.03) and in normal thyroid tissue (n = 2, 7.0 ± 3.1 AU) compared with tissue from patients with Graves’ disease (GD; n = 13; 27.9 ± 10.3 AU), non‐toxic multinodular goitre (NTG; n = 5; 20.9 ± 5.8 AU) and perinodular tissue from TA patients (20.3 ± 4.0 AU). Higher levels were detected in tissues from patients with Hashimoto’s thyroiditis (HT; n = 2; 51.3 ± 10.3 AU). Cultures of pure thyroid‐derived fibroblasts (46 ± 18 AU), thyrocytes (33 ± 8 AU), and the anaplastic thyroid carcinoma cell lines 8505 C (39 ± 11 AU), SW 1736 (214 ± 16 AU) and C 643 (3 ± 1 AU) showed significantly lower TNF‐α mRNA levels than thyroid‐derived lymphocytes (1650 ± 32 AU). TNF‐α was detected in the supernatants of unstimulated lymphocytes (22.1 ± 1.1 pg/ml) and SW 1736 cells (3.5 ± 0.9 pg/ml), but not in unstimulated fibroblasts and thyrocytes. Using an intracellular labelling technique in flow cytometry, the immunophenotype of stimulated TNF‐α‐positive lymphocytes was determined as predominantly CD3+CD45RO+. Our results suggest that TNF‐α is present in the thyroid tissue of different thyroid disorders. Thyroid‐derived lymphocytes are potential TNF‐α producers and may thus locally influence thyroid function.

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