| HOME | HELP | CONTACT US | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
An immunoradiometric assay (IRMA) for the measurement of insulin-like growth factor-II (IGF-II) in human plasma has been developed, optimized and evaluated clinically in normal subjects and patients with disorders of the GH/IGF-I axis. Six monoclonal antibodies (MAbs) to recombinant human IGF-II (rhIGF-II) were produced, all of which had low cross-reactivity with rhIGF-I (< 0·01%) and insulin (< 0·01%). Compatibility of pairs of MAbs was tested in two-site IRMAs using three radioiodinated MAbs and three MAbs linked to Sephacryl S-300 (with separation of bound and free radiolabelled MAb by sucrose layering). Seven pairs of MAbs bound rhIGF-II and the combination of 125I-labelled W3D9 and W2H1 linked to solid phase was selected. The optimized assay had a completion time of 4 h, a minimum detection limit of 30 ng/ml (2·5 standard deviations from the zero standard) and detected a single peak of endogenous IGF-II in normal plasma which co-eluted with rhIGF-II after acid gel chromatography.
IGF-II was measured in formic acid/acetone extracts of plasma from 16 normal subjects (mean 685, range 516–1008 µg/l), four acromegalic patients (mean 637, range 553–700 µg/l), fourteen patients with type-1 diabetes (mean 635, range 247–753 µg/l), nine patients with uraemia (mean 423, range 78–850 µg/l), and three patients with Laron-type GH insensitivity (75, 35 and 36 µg/l). No significant fluctuations were detected between samples obtained hourly from 08.00 to 19.00 h in normal subjects.
Low levels of IGF-binding proteins (IGFBPs) remaining in plasma extracts may interfere with the measurement of IGF-II and give rise to falsely elevated IGF-II levels in radioimmunoassays or falsely suppressed levels in IRMAs. Such interference did not occur with the IRMA when used to measure IGF-II in extracts from normal subjects, acromegalic patients and patients with type-1 diabetes, and the addition of excess rhIGF-I in order to displace IGF-II from residual IGFBPs had no effect on IGF-II measurements in these samples. However, levels of IGF-II measured in extracts from patients with Laron-type GH insensitivity and patients with uraemia increased markedly after preincubation with excess rhIGF-I. The accurate measurement of IGF-II by IRMA in extracts from these subjects therefore requires the displacement of IGF-II from IGFBPs prior to assay. We conclude that, in contrast to radioimmunoassays, the two-site IRMA developed here provides a practical, rapid and specific method for the measurement of IGF-II in human plasma.
Journal of Endocrinology (1993) 137, 141–150
This article has been cited by other articles:
|
|
 |
|
  F. Meyer, P. Galan, P. Douville, I. Bairati, P. Kegle, S. Bertrais, S. Czernichow, and S. Hercberg A Prospective Study of the Insulin-Like Growth Factor Axis in Relation with Prostate Cancer in the SU.VI.MAX Trial Cancer Epidemiol. Biomarkers Prev., September 1, 2005; 14(9): 2269 - 2272. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. G. Miller, J. D. Aplin, and M. Westwood Adenovirally Mediated Expression of Insulin-Like Growth Factors Enhances the Function of First Trimester Placental Fibroblasts J. Clin. Endocrinol. Metab., January 1, 2005; 90(1): 379 - 385. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Kaushal, A. H. Heald, K. W. Siddals, M. S. Sandhu, D. B. Dunger, J. M. Gibson, and N. J. Wareham The Impact of Abnormalities in IGF and Inflammatory Systems on the Metabolic Syndrome Diabetes Care, November 1, 2004; 27(11): 2682 - 2688. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. S. Sandhu, J. M. Gibson, A. H. Heald, D. B. Dunger, and N. J. Wareham Association between Insulin-Like Growth Factor-I: Insulin-Like Growth Factor-Binding Protein-1 Ratio and Metabolic and Anthropometric Factors in Men and Women Cancer Epidemiol. Biomarkers Prev., January 1, 2004; 13(1): 166 - 170. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. H. Heald, K.W. Siddals, W. Fraser, W. Taylor, K. Kaushal, J. Morris, R. J. Young, A. White, and J. M. Gibson Low Circulating Levels of Insulin-Like Growth Factor Binding Protein-1 (IGFBP-1) Are Closely Associated With the Presence of Macrovascular Disease and Hypertension in Type 2 Diabetes Diabetes, August 1, 2002; 51(8): 2629 - 2636. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. K. Cruickshank, A. H. Heald, S. Anderson, J. E. Cade, J. Sampayo, L. K. Riste, A. Greenhalgh, W. Taylor, W. Fraser, A. White, et al. Epidemiology of the Insulin-like Growth Factor System in Three Ethnic Groups Am. J. Epidemiol., September 15, 2001; 154(6): 504 - 513. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Bajoria, M. J. Gibson, S. Ward, S. R. Sooranna, J. P. Neilson, and M. Westwood Placental Regulation of Insulin-Like Growth Factor Axis in Monochorionic Twins with Chronic Twin-Twin Transfusion Syndrome J. Clin. Endocrinol. Metab., July 1, 2001; 86(7): 3150 - 3156. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Westwood, J.M. Gibson, S. R. Sooranna, S. Ward, J. P. Neilson, and R. Bajoria Genes or placenta as modulator of fetal growth: evidence from the insulin-like growth factor axis in twins with discordant growth Mol. Hum. Reprod., April 1, 2001; 7(4): 387 - 395. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. H. Aguiar-Oliveira, M. S. Gill, E. S. de, A. Barretto, M. R. S. Alcântara, F. Miraki-Moud, C. A. Menezes, A. H. O. Souza, C. E. Martinelli, F. A. Pereira, et al. Effect of Severe Growth Hormone (GH) Deficiency due to a Mutation in the GH-Releasing Hormone Receptor on Insulin-Like Growth Factors (IGFs), IGF-Binding Proteins, and Ternary Complex Formation Throughout Life J. Clin. Endocrinol. Metab., November 1, 1999; 84(11): 4118 - 4126. [Abstract] [Full Text]
|
|
| HOME | HELP | CONTACT US | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
