Diaz J L, Wilkin T J
Department of Medicine II, General Hospital, Southampton, U.K.
Clin Chem. 1988 Feb;34(2):356-9.
Four human insulins and four porcine insulins, each monoiodinated to the same specific activity at one of the four tyrosine residues (A14, A19, B16, B26) and purified by reversed-phase liquid chromatography, were tested in a radiobinding assay against a panel of insulin-antibody (IA)-positive sera from 10 insulin-treated diabetics and insulin-autoantibody-positive (IAA) sera from 10 nondiabetics. Of the 10 IAA-positive sera, five were fully cross reactive with both insulin species, and five were specific for human insulin. The rank order of binding of sera with the four ligands from each species was random for IA (mean rank values of 1.9 for A14, 2.0 for A19, 2.5 for B16, and 3.6 for B26 from a possible ranking range of 1 to 4), but more consistent for non-human-insulin-specific IAA (mean rank values 1.3 for A14, 3.8 for A19, 1.7 for B16, and 3.2 for B26 for labeled human insulins; 1.2 for A14, 4.0 for A19, 1.8 for B16, and 3.0 for B26 for labeled porcine insulins). The rank order of binding was virtually uniform for human-insulin-specific IAA (mean values 1.2 for A14, 3.0 for A19, 1.8 for B16, and 4.0 for B26). The influence of iodination site on the binding of labeled insulin appears to be dependent on the proximity of the labeled tyrosine to the antibody binding site and the clonal diversity, or restriction, of insulin-binding antibodies in the test serum. When IA and IAA are measured, the implications of this study regarding the choice of assay ligand may be important.
四种人胰岛素和四种猪胰岛素，每种都在四个酪氨酸残基（A14、A19、B16、B26）之一处单碘化至相同的比活性，并通过反相液相色谱法纯化，在放射结合试验中针对来自10名接受胰岛素治疗的糖尿病患者的一组胰岛素抗体（IA）阳性血清和来自10名非糖尿病患者的胰岛素自身抗体阳性（IAA）血清进行了测试。在10份IAA阳性血清中，5份与两种胰岛素完全交叉反应，5份对人胰岛素具有特异性。对于IA，每种胰岛素的四种配体与血清结合的排名顺序是随机的（A14的平均排名值为1.9，A19为2.0，B16为2.5，B26为3.6，可能的排名范围为1至4），但对于非人类胰岛素特异性IAA则更一致（标记人胰岛素时，A14的平均排名值为1.3，A19为3.8，B16为1.7，B26为3.2；标记猪胰岛素时，A14为1.2，A19为4.0，B16为1.8，B26为3.0）。对于人胰岛素特异性IAA，结合的排名顺序几乎是一致的（A14的平均值为1.2，A19为3.0，B16为1.8，B26为4.0）。碘化位点对标记胰岛素结合的影响似乎取决于标记酪氨酸与抗体结合位点的接近程度以及测试血清中胰岛素结合抗体的克隆多样性或限制性。在测量IA和IAA时，本研究对于测定配体选择的影响可能很重要。
