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.