Nb-2 cell bioassay is not specific for evaluating the biological activity of growth hormone (GH) since it relies on the ability of the hormone to Produce effects by cross-reacting with the lactogenic receptor of Nb-2 cells. We inhibited the mitogenic effect of the other lactogenic hormone that is human prolactin (hPRL), by adding a specific antibody against hPRL to each assay. The aim of the present work was to evaluate whether our modified Nb-2 bioassay was capable of assessing the biological activity alone of bGH We compared serum GH measurements using an immunofluorometric assay (IFMA) and the Nb-2 cell bioassay in serum samples collected from 11 idiopathic GH-deficient children, age range 1.2-14 years, before and, then, 6 and 24 hours following the 1st injection of r-bGH (0.1 IU/Kg sc). Serum GH values evaluated by both IFMA and Nb-2 bioassay significantly (p lt 0.0001) increased 6 hours after GH administration (from 1.36 +- 0.81 to 12.59 +- 1.77 ng/ml and from 0.55 +- 0.09 to 1.56 +- 0.24 U/ml, respectively), and decreased to reach basal levels after 24 hours. In conclusion, the Nb-2 cell bioassay with minor modifications seems to provide a specific and sensitive assessment of the biological activity of GH.
Growth hormone bioactivity evaluated by Nb-2 cell bioassay
TATO', Luciano
1996-01-01
Abstract
Nb-2 cell bioassay is not specific for evaluating the biological activity of growth hormone (GH) since it relies on the ability of the hormone to Produce effects by cross-reacting with the lactogenic receptor of Nb-2 cells. We inhibited the mitogenic effect of the other lactogenic hormone that is human prolactin (hPRL), by adding a specific antibody against hPRL to each assay. The aim of the present work was to evaluate whether our modified Nb-2 bioassay was capable of assessing the biological activity alone of bGH We compared serum GH measurements using an immunofluorometric assay (IFMA) and the Nb-2 cell bioassay in serum samples collected from 11 idiopathic GH-deficient children, age range 1.2-14 years, before and, then, 6 and 24 hours following the 1st injection of r-bGH (0.1 IU/Kg sc). Serum GH values evaluated by both IFMA and Nb-2 bioassay significantly (p lt 0.0001) increased 6 hours after GH administration (from 1.36 +- 0.81 to 12.59 +- 1.77 ng/ml and from 0.55 +- 0.09 to 1.56 +- 0.24 U/ml, respectively), and decreased to reach basal levels after 24 hours. In conclusion, the Nb-2 cell bioassay with minor modifications seems to provide a specific and sensitive assessment of the biological activity of GH.
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