碘缺乏和碘过量对甲状腺自身免疫影响的实验研究

目的观察碘对大鼠免疫细胞(CD4/CD8)、甲状腺球蛋白抗体(thyroglobulin autoanti-body,TGAb)、甲状腺过氧化物酶抗体(thyroid peroxidase autoantibody,TPOAb)的作用,探讨碘对甲状腺自身免疫应答的影响。方法将Wistar大鼠分为6组(1)低碘组(LI)摄碘量<1μg/d;(2)适碘组(NI)摄碘量为6.15μg/d;(3)5倍碘组(5HI)摄碘量为30.75μg/d;(4)10倍碘组(10HI)摄碘量为61.50μg/d;(5)50倍碘组(50HI)摄碘量为307.50μg/d;(6)100倍碘(100HI)摄碘量为615.00μg/d。采用流式细胞仪检测外周血CD4和CD8免疫细胞数量,应用放射免疫分析法(RIA)检测血清中TGAb和TPOAb水平。结果LI组大鼠外周血CD4细胞为(57.9±4.3)%,NI组为(51.2±4.9)%,两组比较,差异有统计学意义。100HI组CD8细胞为(18.4±3.1)%,NI组为(26.5±4.1)%,两组比较,差异有统计学意义。LI组CD4/CD8比值为2.4±0.40,100HI组为2.7±0.4,均高于NI组的1.9±0.3。LI组TGAb含量为(1510±221)CPM,明显低于NI组的(2099±220)CPM;50HI组和100HI组的TGAb含量分别为(3986±286)和(3550±378)CPM,较NI组明显升高。TPOAb含量在10HI组和50HI组分别为(2066±184)和(2141±163)CPM,均明显低于NI组的(2372±245)CPM。结论碘会直接或间接影响CD4/CD8细胞数量和甲状腺自身抗体(TGAb、TPOAb)生成水平,参与甲状腺自身免疫反应。低碘或100倍高碘的摄入,可不同程度地激活Wistar大鼠的免疫状态。在甲状腺自身免疫应答中,碘对甲状腺球蛋白和甲状腺过氧化物酶抗原的影响不相同。

Experimental study on effects of iodine deficiency and excess on thyroid autoimmunity

OBJECTIVE: To observe the effects of iodine on the level of CD4/CD8 cells and the production of thyroglobulin autoantibody (TGAb) and thyroid peroxidase autoantibody (TPOAb) in Wistar rats and to investigate the role of iodine in thyroid autoimmunity. METHODS: Rat models with different iodine intakes including low iodine (LI,), normal iodine (NI,), 5 times normal iodine (5HI), 10 times normal iodine (10HI), 50 times normal iodine (50HI) and 100 times normal iodine (100HI) were established. The amount of iodine intake per rat per day in every group was about < 1, 6.15, 30.75, 61.50, 307.50, 615.00 microg separately. The levels of CD4 and CD8 immune cells in peripheral blood were measured by using flow cytometry. Radioimmunoassay (RIA) was used to determine the titers of TGAb and TPOAb in the serum. RESULTS: In peripheral blood, the level of CD4 cells in LI group was (57.9 +/- 4.3)%, being much higher than in NI group (51.2 +/- 4.9)%. When the level of CD8 cells in 100HI group was (18.4 +/- 3.1)% showing significantly lower than in NI group (26.5 +/- 4.1)%, thus making the ratio of CD4/CD8 cells in the above two groups (LI: 2.4 +/- 0.40 and 100 HI: 2.7 +/- 0.4) higher than in NI group (1.9 +/- 0.3). As comparing with NI group (2099 +/- 220) CPM, the level of TGAb in LI group (1510 +/- 221) CPM was significantly decreased; while in 50HI group (3986 +/- 286) and 100HI group (3550 +/- 378) CPM, the levels of TGAb were both increased, and the levels of TPOAb in 10HI group (2066 +/- 184) CPM and in 50HI group (2141 +/- 163) CPM were both distinctly lower than in NI group (2372 +/- 245) CPM. CONCLUSIONS: Iodine might exert influence on the level of CD4/CD8, and thus the production of thyroid antibodies might directly or indirectly take part in the process of thyroid autoimmunity. Both low iodine and 100 times normal iodine intakes might activate the immune state on some degrees. The effects of iodine on immune responses of TG and TPO antigen in thyroid autoimmunity might not be completely the same.