TSHR胞外区中间段在BALB/c小鼠体内的免疫原性研究

Characterization of the middle segment of the TSHR extracellular domain as immunogens in BALB/c mice

目的观察促甲状腺激素受体(TSHR)胞外区中间段(TSHRm)的免疫调节作用,探讨TSHR分子结构与功能的关系。方法将血蓝蛋白与原核表达的人TSHRm融合蛋白耦联,间隔15d注入BALB/c小鼠腹腔内共5次,对照组注射生理盐水;检测动物血清T_4、促甲状腺激素受体抗体(TRAb)、促甲状腺激素受体刺激抗体(TSAb)、促甲状腺激素受体阻滞抗体(TBAb)水平及甲状腺组织病理变化。结果对照组动物T_4水平升高后下降,TRAb水平较实验前升高,TSAb、TBAb无显著变化。实验组动物T_4总体水平一直保持升高趋势;免疫30 d时血清TRAb水平显著升高(P<0.001),TSAb、TBAb水平变化表现为先升后降。甲状腺组织的病理变化为甲状腺上皮细胞增生和淋巴细胞浸润。结论人TSHRm融合蛋白可刺激小鼠产生TRAb、TSAb和TBAb,其对动物机体的影响反映了TSAb和TBAb综合作用的结果,表明TSHRm可能具有TSAb及TBAb两种抗原表位。

Objeelive To observe the immunological effect of the middle segment of the TSHR extracellular domain （TSHRm） and investigate the structure-activity relationship of the TSHR molecule. Methods The fusion protein of human TSHRm, which was obtained from prokaryote expression, was coupled with keyhole limpets hemocyanin（KLH） to produce a complex. This complex was injected into the abdominal cavity of the BALB/c mice by each 15 days for five times. As control, the mice were given the normal saline. The levels of serum T4, thyrotropin receptor stimulating antibody （TSAb） and thyrotropin receptor blocking antibody （TBAb） were measured by RIA. Thyrotropin receptor antibody （TRAb） was measured by ELISA. The animals were killed on the day 60. Then, the thyroid was taken out for observing the pathological changes. Results The level of T4 was increased, then showed a trend of falling; TRAb was increased（ P 〈 0.05） ; TSAb and TBAb didn＇t show significant difference in the control animals. In experimental animals, the levels of T4 kept in a rising trend; TRAb increased significantly on the day 30（ P 〈 0. 001 ） ; TSAb and TBAb showed a decreasing trend after a rising trend. In experimental group, there was epithelia proliferation or flatted epithelia and some lymphocyte infiltration in thyroid folficle. Conclusions The results show that the fusion protein of human TSHRm may induce the production of the TRAb, including TSAb and TBAb, in the BALB/c mice. Its effects on the animal were involved in the action of TSAb and TBAb. It indicates that the TSHRm may contain the epitopes, both TSAb and TBAb.