Strasburger C J, Wu Z, Pflaum C D, Dressendörfer R A
Medical Clinic, Innenstadt University Hospital, Ludwig Maximilians University, Munich, Germany.
J Clin Endocrinol Metab. 1996 Jul;81(7):2613-20. doi: 10.1210/jcem.81.7.8675586.
Confirmation of the diagnosis of GH deficiency in adults and children involves provocative testing for human (h) GH. Different commercially available immunoassays yield largely discrepant results in the measurement of GH levels in human serum. These discrepancies result in doubtful relevance of cut-off levels proposed for GH provocative testing. We have developed an immunofunctional assay method that allows quantitation of only those GH forms in circulation that possess both binding sites of the hormone for its receptor and thus can initiate a biological signal in target cells. An anti-hGH monoclonal antibody recognizing binding site 2 of hGH is immobilized and used to capture hGH from the serum sample. Biotin-labeled recombinant GH-binding protein in a second incubation step forms a complex with those hGH molecular isoforms that have both binding sites for the receptor. The signal is detected after a short third incubation step with labeled streptavidin. The assay is sensitive (detection range, 0.1-100 micrograms/L) and has average inter- and intraassay precisions of 10.3% and 7.3% respectively. Endogenous GH-binding protein does not interfere with the hGH result; placental lactogen slows no detectable cross-reaction in this immunofunctional assay. The degree of immunofunctionally active hGH forms in serum samples, calculated by comparison of immunofunctional assay and RIA results, varied between 52-93%. We propose this immunofunctional assay for GH measurement as a new reference method for hGH quantitation in serum. The immunofunction assay translates only hGH forms into an assay signal that are capable of dimerizing GH receptors and, thus, of initiating a biological effect in target cells.
成人和儿童生长激素（GH）缺乏症的诊断确认涉及对人（h）GH进行激发试验。不同的市售免疫测定法在测量人血清中GH水平时产生的结果差异很大。这些差异导致了为GH激发试验提出的临界值的相关性存疑。我们开发了一种免疫功能测定方法，该方法仅允许对循环中具有该激素与其受体的两个结合位点、从而能够在靶细胞中启动生物信号的那些GH形式进行定量。一种识别hGH结合位点2的抗hGH单克隆抗体被固定化，并用于从血清样本中捕获hGH。在第二步孵育中，生物素标记的重组GH结合蛋白与那些具有受体两个结合位点的hGH分子异构体形成复合物。在第三步短暂孵育后，用标记的链霉亲和素检测信号。该测定法灵敏（检测范围为0.1 - 100微克/升），平均批间和批内精密度分别为10.3%和7.3%。内源性GH结合蛋白不干扰hGH结果；在该免疫功能测定中，胎盘催乳素未显示出可检测到的交叉反应。通过比较免疫功能测定和放射免疫分析（RIA）结果计算得出，血清样本中免疫功能活性hGH形式的程度在52% - 93%之间变化。我们提议将这种用于GH测量的免疫功能测定法作为血清中hGH定量的一种新的参考方法。该免疫功能测定法仅将能够使GH受体二聚化、从而能够在靶细胞中启动生物学效应的hGH形式转化为测定信号。
