RESUMEN
In order to study the effect of excessive iodine on immune function of lymphocytes and the role of selenium supplementation with excessive iodine intake, the changes of T lymphocyte number, ratio of subsets, activity of natural killer (NK) cells and lymphocytes proliferation response were investigated. 150 female BALB/C mice were randomly divided into 5 groups in terms of their body weight (n=30 in each group), and 10 of each group were taken as one batch for test. Mice in the 5 groups were orally administrated with iodine 0 (group Ⅰ ), 1500 (group Ⅱ), 3000 (group Ⅲ),6000 μg/L (group Ⅳ), iodine 6000 μg/L plus selenium 0.3 mg/L (group Ⅴ) respectively for 30 days.Lymphocyte proliferation response, CD4+/CD8+, Th1/Th2 and the activity of NK cells were measured. CD4+/CD8+ was significantly lower, while lymphocyte proliferation response stronger, and Th1/Th2 and the activity of NK cells significantly higher in group Ⅳ than in group Ⅰ (P＜0.01).There was no significant difference in all indexes between group Ⅴ and group Ⅰ (P＞0.05). It was suggested that excessive iodine as exogenous chemical materials can induce disorders of T lymphocyte immune function in mice. 0.3 mg/L selenium supplementation can protect mice against toxicity induced by 6000 μg/L iodine.
RESUMEN
For the first time,the iodine-induced thyroid diseases group of China Medical University has finished a five-year prospective epidemiological study on the incidences of thyroid diseases in the three communities with various levels of iodine intake.The results indicated that increased incidences of subclinical hypothyroidism and autoimmune thyroiditis in the communities with more than adequate and excessive iodine intake.The individuals with positive thyroid autoantibodies at baseline more likely became hypothyroid due to more than adequate and excessive iodine intake.These adverse effects are mainly involved in the susceptible populations for thyroid diseases.Hence it appears to be reasonable that iodine supplementation should be conducted by localization and individualization.