Iodine deficiency induces thyroid autoimmune reactivity in Wistar rats.
The last 2 decades it has become clear that iodine deficiency has a modulating effect on the thyroid autoimmune response in humans. Also, in animals that spontaneously develop autoimmune thyroid disease, evidence is accumulating that a low iodine intake can modulate thyroid autoimmune reactivity. However, it is still not clear what the effect of a low iodine intake on thyroid autoimmune reactivity is in normal nonautoimmune animals. To study the relationship of a dietary low iodine intake on the thyroid autoimmune reactivity in nonautoimmune animals, normal Wistar rats (female) were kept on an enriched iodine diet (daily iodine intake of 100 micrograms iodine), a "for our area normal" (conventional) diet (COD; daily iodine intake of 7 micrograms iodine), a low iodine diet (LID; 2 days of 1% KCLO4, followed by iodine-deficient drinking water/pellets), or an extremely low iodine diet (LID+; 1% KCLO4 continuously in the drinking water and iodine-deficient pellets). The enriched iodine diet rats were euthyroid (T3, approximately 8 nM/liter: T4, approximately 50 nM/liter; TSH, approximately 2 ng/ml), had a normal thyroid weight (approximately 12.5 mg), and showed only minimal signs of local thyroid immune reactivity; low numbers of intrathyroidal dendritic cells (DC; approximately 35 DC/mm2), CD4+ cells (approximately 2 cells/mm2), and CD8+ cells (approximately 2.5 cells/mm2) were found in combination with low anticolloid antibody production (incidence of positive animals, 12.5%). The COD resulted in a normal thyroid function. The rats were euthyroid (range of T3, 1.6-1.2 nM/liter; T4, approximately 50 nM/liter; TSH, approximately 2 ng/ml) and had a normal thyroid weight (approximately 12.5 mg). However, some signs of thyroid autoimmune reactivity were found [number of intrathyroidal DC, approximately 40/mm2; approximately 3 CD4-positive (CD+) cells/mm2; approximately 3 CD8+ cells/mm2; together with a 30% incidence of anticolloid antibodies]. The LID and LID+ not only induced goiter formation [thyroid weight, 27.3 +/- 4.2 mg (mean +/- SD) after 12 weeks of LID and 38.4 +/- 5.3 mg after 4 weeks of LID+] and low production of T4 by the thyroid [28 +/- 3 nM/liter (mean +/- SD)] after 12 weeks of LID and 14 +/- 3 nM/liter after 2 weeks of LID+], but also induced various signs of thyroid autoimmune reactivity.(ABSTRACT TRUNCATED AT 400 WORDS)
Mooij
P
P
Department of Immunology, Erasmus University, Rotterdam, The Netherlands.
de Wit
H J
HJ
Bloot
A M
AM
Wilders-Truschnig
M M
MM
Drexhage
H A
HA
D000818:Animals; D001323:Autoantibodies / Q000096:biosynthesis; D001327:Autoimmune Diseases / Q000139:chemically induced*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology; D016827:CD8 Antigens / Q000032:analysis; D004032:Diet; D005260:Female; D006042:Goiter / Q000209:etiology; D007455:Iodine / Q000008:administration & dosage / Q000172:deficiency* / Q000652:urine; D007958:Leukocyte Count; D008214:Lymphocytes / Q000276:immunology / Q000473:pathology; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D013959:Thyroid Diseases / Q000139:chemically induced / Q000276:immunology*; D013961:Thyroid Gland / Q000276:immunology / Q000473:pathology
D001323:Autoantibodies; D016827:CD8 Antigens; D007455:Iodine