AN INVESTIGATION INTO THE LABILITY OF THE BIOACTIVITY OF HUMAN GROWTH-HORMONE USING THE ESTA BIOASSAY

Citation
Mt. Dattani et al., AN INVESTIGATION INTO THE LABILITY OF THE BIOACTIVITY OF HUMAN GROWTH-HORMONE USING THE ESTA BIOASSAY, Hormone research, 46(2), 1996, pp. 64-73
Citations number
23
Categorie Soggetti
Endocrynology & Metabolism
Journal title
ISSN journal
03010163
Volume
46
Issue
2
Year of publication
1996
Pages
64 - 73
Database
ISI
SICI code
0301-0163(1996)46:2<64:AIITLO>2.0.ZU;2-H
Abstract
We compared the bioactivity attributable to human growth hormone (hGH) in serum samples, determined at the time of their collection, with th at after storage for 2-18 months at -20 degrees C. The samples were ob tained from volunteers and patients who underwent provocative tests of hGH secretion, and the bioactivity was determined in the ESTA bioassa y, which is based upon the use of Nb2 cells. We report that, in some s ubjects, the bioactivity of samples collected at the response peaks de teriorated on storage for as little as 2 months. The decrease in hGH b ioactivity was systematic in that it consistently declined so as to ap proach the values initially determined by an immunoassay (Hybritech IR MA). This differential lability was a characteristic of the peak sampl es, and was not observed for either samples collected before and after the peaks of hGH secretion or for purified preparations of hGH which were subjected to a range of freeze/thaw and storage regimens. We sugg est that this unusual lability is indicative of transient shifts in th e spectrum of the variants of hGH which are present in the circulation following stimulation by provocative agents. This study emphasises th e need to minimise the risk of introducing storage artefacts in invest igations into the responses of hGH to provocation.