Analysis of autoantibodies in the mechanism of the occurrence of multiple autoimmune endocrinopathies

我们建立了一种检测抗垂体抗体（APA）的方法作为筛选试验，采用酶联免疫吸附试验（ELISA），并评价了其临床应用价值。采用大鼠垂体细胞可溶性部分作为ELISA/APA抗原。该试验与利用间接酶自身抗体的试验类似。通过比色反应和450 nm吸光度计算出该方法的截断指数（ci值）。自身免疫性甲状腺疾病（桥本甲状腺炎）患者约20% ELISA/APA阳性。另一方面，桥本甲状腺炎和Graves病分别有34%和28%的Western blot分析阳性带，与22 kDa蛋白一致。此外，39%的胰岛素依赖型糖尿病（IDDM）患者ELISA/APA阳性，其中64%的患者Western blot分析阳性。接下来，我们用Western blot方法分析了22 kDa蛋白，这是与APA匹配的抗原之一。对该蛋白进行氨基酸序列分析，从N端得到P-A-M-L-S-S-L-F-N-A-V-L-R。通过同源性分析，发现该匹配抗原与生长激素的分子量相同。需要进一步的研究来确定其他阳性带的性质，通过Western blot分析。如前所述，一些垂体侏儒症和全垂体功能减退症患者表现为APA阳性。在这些观察的基础上，本研究表明，测量APA是多种自身免疫性内分泌病变的有用指标。

We have established an assay method of antipituitary antibodies (APA) as a screening test, using enzyme-linked immunosorbent assay (ELISA) and evaluated on its clinical usefulness. The soluble fractions of rat pituitary cells were used as antigens of ELISA/APA.The assay, similar to that utilized indirect enzyme autoantibodies, was performed. The results by this assay method were calculated as the cut off index (C.I value), using colorimetric reaction and absorvance at 450 nm.Pathiens with autoimmune thyroid diseases (Hashimoto's thyroiditis Graves, disease) showed approximately 20% positive for ELISA/APA.On the other hand, 34% in Hashimoto's thyroiditis and 28% in Graves disease had a positive band by Western blot analysis, which was identical with 22 kDa protein. Furthermore, 39% in patients with insulin-dependent diabetes mellitus (IDDM) was positive for ELISA/APA,in which 64% in such patients was positive by Western blot analysis.We next analyzed 22 kDa protein ontained by Western blot method, which was one of matched antigens to APA.The analysis of amino acid sequence in this protein resulted in P-A-M-L-S-S-L-F-N-A-V-L-R from the N terminal side. Employing homology analysis, this matched antigens was found to be identical with molecular weight of somatotropin.Further studies are needed to determine the nature of other positive bands by Western blot analysis. As reported previously, some patients with pituitary dwarfism and panhypopituitarism showed positive APA.On the basis of these observations, the present study suggests that measurements of APA are a useful indicator of multiple autoimmune endocrinopathies.