Masure H R, Jaffee W L, Sickel M A, Birken S, Canfield R E, Vaitukaitis J L
J Clin Endocrinol Metab. 1981 Nov;53(5):1014-20. doi: 10.1210/jcem-53-5-1014.
Urine obtained from normal pregnant women as well as from patients with hCG-secreting tumors frequently contains native hCG and free hCG subunits when separated on Sephadex G-100. In addition, a small amount of an immunoreactive, hCG-like, low molecular weight substance is usually observed in those chromatograms and represents less than 1% of the total immunoreactive hCG present. Two patients with widely metastatic hCG-secreting tumors excreted disproportionately large quantities of that low molecular weight substance, and that observation raised the possibility that this substance was a secretory and not a degradative product of the hCG molecule. The small immunoreactive hCG-like substance was subsequently characterized immunologically, biologically, and physically. The hCG fragment displayed a biphasic dose-response line in a homologous hCG RIA. The slope of the upper portion of the dose-response line was equal to that for native hCG, but the slope of the lower component of the dose-response line was significantly different from that for hCG. The immunoreactive hCG substance cross-reacted with hCG beta but not with either hCG alpha or hCG beta carboxyl-terminus. The small molecular size immunoreactive hCG-like substance bound to Concanavalin A-Sepharose 4B and eluted with 0.2 M alpha-D-methyl glucopyranoside, contained no significant intrinsic biological activity when tested in the in vitro Leydig cell bioassay and also failed to compete with labeled hCG for specific ovarian LH/hCG receptors. Consequently, that small urinary immunoreactive hCG substance behaved neither as a hCG agonist or antagonist. It exhibited a plasma half-life of 4.5 min when the appropriate Sephadex G-100 fractions were injected into immature female rats. The small molecular size immunoreactive hCG-like substance may be a secretory or breakdown product of hCG-secreting cells.
从正常孕妇以及分泌人绒毛膜促性腺激素（hCG）的肿瘤患者体内获取的尿液，在经葡聚糖凝胶G - 100分离时，通常含有天然hCG和游离hCG亚基。此外，在这些色谱图中通常会观察到少量具有免疫反应性、类似hCG的低分子量物质，其含量不到总免疫反应性hCG的1%。两名患有广泛转移的分泌hCG肿瘤的患者排出了数量不成比例的大量该低分子量物质，这一观察结果增加了这种物质是hCG分子的分泌产物而非降解产物的可能性。随后，对这种小的具有免疫反应性的类似hCG物质进行了免疫学、生物学和物理特性鉴定。该hCG片段在同源hCG放射免疫分析（RIA）中呈现双相剂量反应曲线。剂量反应曲线上部的斜率与天然hCG的斜率相等，但剂量反应曲线下部成分的斜率与hCG的斜率显著不同。该具有免疫反应性的hCG物质与hCGβ发生交叉反应，但与hCGα或hCGβ羧基末端均无交叉反应。这种小分子量的具有免疫反应性的类似hCG物质与伴刀豆球蛋白A - 琼脂糖4B结合，并用0.2Mα - D - 甲基吡喃葡萄糖苷洗脱，在体外睾丸间质细胞生物测定中测试时不具有明显的内在生物活性，并且也不能与标记的hCG竞争特异性卵巢促黄体生成素/ hCG受体。因此，这种小的尿液中具有免疫反应性的hCG物质既不表现为hCG激动剂也不表现为拮抗剂。当将适当的葡聚糖凝胶G - 100级分注入未成熟雌性大鼠体内时，它的血浆半衰期为4.5分钟。这种小分子量的具有免疫反应性的类似hCG物质可能是分泌hCG细胞的分泌产物或分解产物。
