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Objective: Interferon regulatory factor-1 (IRF-1) is a critical regulator of interferon-g (IFNg)-mediated immune responses. To determine whether IRF-1 is involved in the pathogenesis of thyroiditis in animal models, we evaluated the incidence of iodide-induced lymphocytic thyroiditis (LT) in nonobese diabetic (NOD) mice lacking IRF-1 as well as IRF-1 þ/þ and þ /2 mice. Design: IRF-1 þ /þ , þ/2 and 2 /2 NOD mice at 6 weeks of age were fed water (group 1) or iodide water (group 2) for 8 weeks. Methods: Thyroids were examined histopathologically and intrathyroidal lymphocytic infiltration was arbitrarily graded. Serum thyroxine (T 4 ) and anti-mouse thyroglobulin antibody (anti-mTgAb) levels were measured. Spleen cell population was analyzed by flow cytometry, and IFNg and interleukin-10 produced by splenocytes were measured by enzyme-linked immunosorbent assay. Results: In group 1, only 4.3% of NOD mice developed LT. In contrast, 67.6% of mice in group 2 developed the disease. Iodide treatment induced LT in more than 80% of IRF-1 þ/þ and þ/2 mice. However, no IRF-1 2 /2 mice in group 2 developed LT. There was no difference in both serum antimTgAb and T 4 levels among the three IRF-1 genotypes of NOD mice. Numbers of splenic CD8 þ T cells and IFNg production by Concanavalin A-stimulated splenocytes were markedly decreased in IRF-1-deficient NOD mice. Conclusions: IRF-1 is involved in the development of iodide-induced LT in NOD mice.

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Familial dysalbuminemic hyperthyroxinemia (FDH) is a familial autosomal dominant syndrome caused by abnormal albumin with an increased affinity for thyroxine (T4). Two types of mutations in the albumin gene, replacing the normal arginine 218 with a histidine (R218H) or a proline (R218P), have been reported to cause FDH. Here, we report a pregnant Japanese woman with FDH caused by the mutant albumin R218P. She had extremely elevated total T4 levels but normal TSH. While the majority of T4was bound to albumin, T4 binding to thyroxine-binding globulin (TBG) was progressively increased throughout pregnancy. Her infant also had elevated serum T4 but normal thyrotropin (TSH). The presence of a guanine to cytosine transition in the second nucleotide of codon 218 of the albumin gene, resulting in a substitution of proline for the normal arginine (R218P), was revealed in the proband. Serum free thyroxine (FT4) levels were increased when measured with some commercial kits including equilibrium dialysis followed by radioimmunoassay (RIA) but not when determined by RIA after ultrafiltration of sera. These results indicate an increased T4 binding to TBG during pregnancy in the patients with FDH. Furthermore, our results suggest that normal serum FT4 determined by equilibrium dialysis is not an ultimate standard for the diagnosis of FDH in the patients with the mutant albumin R218P.

Continuing antithyroid drug therapy throughout pregnancy prevents postpartum recurrence of Graves' hyperthyroidism without resulting in neonatal hypothyroidism or malformations.