Agin Arnaud, Jeandidier Nathalie, Gasser Françoise, Grucker Daniel, Sapin Rémy
Faculté de Médecine, Université Louis Pasteur, Centre National de la Recherche Scientifique, Unité Mixte de recherche 7004, Institut de Physique Biologique, Strasbourg, France.
Clin Chem Lab Med. 2006;44(11):1379-82. doi: 10.1515/CCLM.2006.257.
In clinical studies involving rapid-acting analogues (RAAs), insulin immunoreactivity is frequently measured, including endogenous, regular insulin (RI) and RAA immunoreactivities. Such a procedure implies equivalent cross-reactivities of all insulins present in serum. Commercially available human insulin immunoassays have been widely used, but their limitations (including hemolysis and anti-insulin antibodies) were not fully investigated. The aims of our study were to compare cross-reactivities of RI and RAAs in buffer and in serum and to investigate insulin immunoassay pitfalls.
Cross-reactivities were assessed using Bi-insulin IRMA (Schering Cis-Bio International) in phosphate-buffered saline (PBS)-1% bovine serum albumin (BSA) and in pools of sera spiked with RI and RAAs (lispro and aspart). To investigate the influence of hemolysis, a pool of sera spiked with RAA was mixed with a concentrated hemolysate (final hemoglobin concentration 10 g/L) and incubated for 3 h at room temperature. To determine interference by anti-insulin antibodies, insulin was removed using charcoal from 18 sera with anti-insulin antibodies and from 17 sera without detectable anti-insulin antibodies. These insulin-free samples were then spiked with RI and RAAs and the immunoreactivity was determined.
Compared with buffer, cross-reactivity in serum for RI, lispro and aspart was lower (35%, 29% and 26% lower, respectively). Hemolysis degraded almost all RI and RAAs contained in the serum (>or=95%). Anti-insulin antibody interference was significant for RI and RAAs (p<or=0.004) and correlated with anti-insulin antibody level in the serum (p<or=0.001).
In serum, RI and RAA cross-reactivities are slightly lower than in buffer. For RAA assessment, hemolysed samples should be discarded and anti-insulin antibodies should be removed from samples before immunoreactivity measurements.
在涉及速效类似物（RAA）的临床研究中，经常测量胰岛素免疫反应性，包括内源性常规胰岛素（RI）和RAA免疫反应性。这种方法意味着血清中所有胰岛素具有等效的交叉反应性。市售的人胰岛素免疫测定法已被广泛使用，但其局限性（包括溶血和抗胰岛素抗体）尚未得到充分研究。我们研究的目的是比较缓冲液和血清中RI和RAA的交叉反应性，并研究胰岛素免疫测定的缺陷。
使用双胰岛素免疫放射分析法（Bi-insulin IRMA，先灵葆雅顺式生物国际公司）在磷酸盐缓冲盐水（PBS）-1%牛血清白蛋白（BSA）以及添加了RI和RAA（赖脯胰岛素和门冬胰岛素）的血清池中评估交叉反应性。为了研究溶血的影响，将添加了RAA的血清池与浓缩溶血产物（最终血红蛋白浓度为10 g/L）混合，并在室温下孵育3小时。为了确定抗胰岛素抗体的干扰，使用活性炭从18份含有抗胰岛素抗体的血清和17份未检测到抗胰岛素抗体的血清中去除胰岛素。然后向这些无胰岛素样品中添加RI和RAA，并测定免疫反应性。
与缓冲液相比，血清中RI、赖脯胰岛素和门冬胰岛素的交叉反应性较低（分别低35%、29%和26%）。溶血使血清中几乎所有的RI和RAA降解（≥95%）。抗胰岛素抗体对RI和RAA的干扰显著（p≤0.004），且与血清中的抗胰岛素抗体水平相关（p≤0.001）。
在血清中，RI和RAA的交叉反应性略低于缓冲液。对于RAA评估，溶血样本应丢弃，在测量免疫反应性之前应从样本中去除抗胰岛素抗体。
