甲状腺激素自身抗体(抗T_3、T_4)放射免疫分析

A Newly Developed RIA for Thyroid Hormone Autoantibodies (THAAb)

目的 :本实验主要建立内源性甲状腺激素自身抗体 (抗T3 、T4)放射免疫分析的检测方法。方法 :用12 5I标记T3 、T4衍生物作为示踪剂 ,血清样本与T3 、T4衍生物 (12 5IT3 、T4衍生物 )在室温 16h孵育。用抗人IgG二抗分离抗体抗原复合物 ,测定放射性活度。结果 :12 5I标记T3 、T4衍生物与人血清T3 、T4自身抗体特异性结合。健康人群中甲状腺激素自身抗体阳性检出率为 1 0 7% ;甲状腺功能异常组甲状腺激素自身抗体阳性检出率为 14 4 % ;甲状腺功能亢进组 13 5 % ;甲状腺功能减退组 15 2 %。甲状腺激素自身抗体阳性血清标本经加入非标记T3 或T4,血清中T3 或T4自身抗体可被中和。T3 或T4自身抗体滴度较原滴度明显下降 (P <0 0 5 ) ,用PEG沉淀法去除血清中免疫球蛋白 ,高水平的FT3 、FT4均明显下降 (P <0 0 5 )。结论 :本文结果提示 ,正常人群中甲状腺自身抗体阳性的发生率较低 ,甲状腺功能异常患者中甲状腺激素自身抗体阳性检出率达14 4 %。内源性甲状腺激素自身抗体对FT3 、FT4的测定存在干扰 ,结果常与临床表现不一致。经PEG将免疫球蛋白去除后 ,重新评估了血清中FT3 、FT4的含量 ,其结果与TSH趋于一致。

Objective To report a newly developed RIA for THAAb from this laboratory. Methods The tested serum samples were cultured with labelled thyroid hormone analogus ( 125 I T 3, 125 I T 4) for 16 hours. Antigen-antibody complex was precipitated with anti-human IgG (immune precipitation method) and radio-activity determined. Results The mean positive rate of THAAb in healthy euthyroid controls (n=186) was only 1.07%. The mean positive rate in patients with thyroid disorders was 14.4% (mean rate 13.5% in hyperthyroid subjects, n=118 and mean rate 15.2% in hypothyroid sabjects, n=72). The serum THAAb titer could be markedly lowered after adding non-labelled thyroid hormones (P<0.05). After PEG precipitation, the original false high levels of FT 3 and FT 4 would be significantly lowered (P<0.05). Conclusion The presence of THAAb in serum could interfere with the determination of FT 3、 FT 3 levels. In patients with positive THAAb (about 14.4% in patients with all thyroid disorders), the FT 3, FT 4 levels were best determined after PEG precipitation.