Effect of excessive iodine on immune function of lymphocytes and intervention with selenium.

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 microg/L (group IV), iodine 6000 microg/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 microg/L iodine.