Bozzola M, Zecca M, Locatelli F, Radetti G, Pagani S, Autelli M, Tatò L, Chatelain P
Department of Paediatrics, University of Pavia, IRCCS Policlinico San Matteo, Italy.
J Endocrinol Invest. 1998 Dec;21(11):765-70. doi: 10.1007/BF03348043.
The Nb2 cell bioassay could be a useful tool for evaluating human growth hormone (hGH) bioactivity, but is not specific for hGH since it relies on the ability of the hormone to produce effects by cross-reacting with the lactogenic receptor on Nb2 cells. We studied the biological activity of both endogenous and exogenous hGH in short patients using the Nb2 bioassay after inhibiting the mitogenic effect of the other lactogenic hormone, that is human prolactin (hPRL), by adding a specific antibody against hPRL to each assay. The in vitro study showed a significant (p<0.0001) increase in Nb2 cell proliferation when increasing concentrations of highly purified hGH were added to the cell culture. A complete inhibition of Nb2 cell replication was observed after adding a specific antibody against hGH. The in vivo study showed a significantly (p<0.0001) lower hGH bioactivity (4.90+/-0.28 ng/ml) evaluated during stimulation tests in 9 children with total idiopathic GH deficiency, mean age 9.25+/-1.99 years, in comparison with that found in 11 short children with normal growth velocity, mean age 8.22+/-1.41 years (12.25+/-1.19 ng/ml). Likewise, serum GH levels measured by immunofluorometric assay IFMA in the same serum samples were significantly (p<0.001) lower in the 9 GH-deficient (1.97+/-0.37 ng/ml) than in the 11 short children (21.85+/-2.71 ng/ml). Moreover, we evaluated GH concentrations using both IFMA and the Nb2 cell bioassay in serum samples collected from another 11 idiopathic GH-deficient children, mean age 10.71+/-1.18 years, before and then, 6 and 24 hours following the 1 st injection of r-hGH (0.1 IU/kg sc). Serum GH values measured by both IFMA and Nb2 bioassay significantly (p<0.0001) increased 6 hours after r-hGH administration and decreased to reach basal levels after 24 hours. In conclusion, the Nb2 cell bioassay with minor modifications seems to provide a specific and sensitive assessment of hGH bioactivity.
Nb2细胞生物测定法可能是评估人生长激素（hGH）生物活性的一种有用工具，但它并非hGH特有的检测方法，因为该方法依赖于hGH与Nb2细胞上的催乳素受体发生交叉反应来产生效应的能力。我们在每个检测中加入抗人催乳素（hPRL）的特异性抗体，抑制另一种催乳素即hPRL的促有丝分裂作用后，使用Nb2生物测定法研究了身材矮小患者体内内源性和外源性hGH的生物活性。体外研究表明，向细胞培养物中添加浓度不断增加的高度纯化hGH时，Nb2细胞增殖显著增加（p<0.0001）。加入抗hGH特异性抗体后，观察到Nb2细胞复制完全受到抑制。体内研究表明，在9名平均年龄为9.25±1.99岁的完全性特发性生长激素缺乏症儿童的刺激试验中，评估的hGH生物活性（4.90±0.28 ng/ml）显著低于（p<0.0001）11名平均年龄为8.22±1.41岁、生长速度正常的身材矮小儿童（12.25±1.19 ng/ml）。同样，在相同血清样本中通过免疫荧光测定法（IFMA）测量的血清GH水平，9名生长激素缺乏症儿童（1.97±0.37 ng/ml）显著低于（p<0.001）11名身材矮小儿童（21.85±2.71 ng/ml）。此外，我们在另外11名平均年龄为10.71±1.18岁的特发性生长激素缺乏症儿童首次注射重组人生长激素（r-hGH，0.1 IU/kg皮下注射）之前、之后6小时和24小时采集的血清样本中，使用IFMA和Nb2细胞生物测定法评估了GH浓度。r-hGH给药6小时后，通过IFMA和Nb2生物测定法测量的血清GH值均显著增加（p<0.0001），并在24小时后降至基础水平。总之，经过微小修改的Nb2细胞生物测定法似乎能对hGH生物活性进行特异性和敏感性评估。
