Specific immunoradiometric assay of insulin-like growth factor i with use of monoclonal antibodies
Scott, M.G.; Cuca, G.C.; Petersen, J.R.; Lyle, L.R.; Burleigh, B.D.; Daughaday, W.H.
Clinical Chemistry 33(11): 2019-2023
1987
ISSN/ISBN: 0009-9147 PMID: 2445506 Document Number: 293898
We identified two monoclonal antibodies that bind spatially distinct epitopes on insulin-like growth factor I (IGF-I). Using these two antibodies, we developed a simultaneous, two-site immunoradiometric assay (IRMA) specific for IGF-I. This IRMA has no detectable cross reactivity with insulin, proinsulin, prolactin, or somatotropin, and less than 2% crossreactivity with IGF-II. The assay response varies linearly with IGF-I concentrations of 0-800 micrograms/L in serum; the detection limit is about 10 micrograms/L. A comparison of 26 IGF-I serum values from the IRMA and from a previously reported IGF-I specific RIA gave a correlation coefficient of 0.96 with no substantial bias (slope = 1.10). IGF-I values for serum, as an aid in assessing growth abnormalities, are easily (only three pipetting steps) obtained in less than 4 h.