IODINE-INDUCED AUTOIMMUNE-THYROIDITIS IN NOD-H-2(H4) MICE

Excess iodine ingestion has been implicated in induction and exacerbat ion of autoimmune thyroiditis in human populations and animal models. We studied the time course and sex-related differences in iodine-induc ed autoimmune thyroiditis in NOD-H-2(h4) mice, This strain, derived fr om a cross of NOD with B10.A(4R), spontaneously develops autoimmune th yroiditis but not diabetes. NOD-H-2(h4) mice were given either plain w ater or water with 0.05% iodine for 8 weeks. Approximately 54% of fema le and 70% of male iodine-treated mice developed thyroid lesions, wher eas only 1 of 20 control animals had thyroiditis at this time. Levels of serum thyroxin (T4) were similar in the treatment and control group s. Thyroglobulin-specific antibodies were present in the iodine-treate d group after 8 weeks of treatment but antibodies to thyroid peroxidas e were not apparent in the serum of any of the animals. Levels of thyr oglobulin antibodies increased throughout the 8-week iodine ingestion period; however, no correlation was seen between the levels of total t hyroglobulin antibodies and the degree of thyroid infiltration at the time of autopsy. The thyroglobulin antibodies consisted primarily of I gG2a, IgG2b, and IgM antibodies with no detectable IgA, IgG1, or IgG3 thyroglobulin-specific antibodies. The presence of lgG2b thyroglobulin -specific antibodies correlated well with the presence of thyroid lesi ons. (C) 1996 Academic Press, Inc.