Monoclonal Antibody Against Human Somatomedin-C/Insulin-Like Growth Factor-I

Abstract

A monoclonal IgG3 antibody produced by mouse hybridoma shows high specificity for human somatomedin-C (SM-C) and insulin-like growth factor-I (IGF-I). The apparent Ka for SM-C is 1.7 x 10(10) M-1. At 1:2000 final dilution, culture medium from antibody-producing cells binds 35-40% of radioiodinated SM and IGF-I tracers, while similar binding is seen with ascites fluid from tumor-bearing mice at 1:200,000 dilution. Rat SM, multiplication stimulating activity, IGF-I C-peptide and human insulin show little or no crossreactivity, while IGF-II has 7%, and IGF-I 70%, of the potency of SM-C. Of a variety of species tested, acid-ethanol extracted guinea pig serum has the greatest immunoreactivity, and extracts of rabbit, rat and mouse serum have the lowest activity. Human plasma extracts give displacement curves parallel to purified SM, and vary in potency depending upon the GH status of the donor. These results suggest that this antibody will be of value for SM-C/IGF-I radioimmunoassay.

Monoclonal Antibodies to Mechano-Growth Factor

“…Although MAbs to IGF-1 have been obtained long ago, (24) to date no investigations dedicated to generation of MAbs against MGF have been reported. As demonstrated in the paper, we obtained two MAbs (4F3 and 8B9) recognizing different antigen determinants.…”

Evidence for a functional role of endogenously produced somatomedinlike peptides in the regulation of DNA synthesis in cultured human fibroblasts and porcine smooth muscle cells.

“…Recently, this laboratory and several others have prepared monoclonal antibodies to Sm-C that are specific for this peptide (10)(11)(12). The antibody designated Sm 1.2 that is currently used in our laboratory has 5% cross-reactivity with human insulinlike growth Factor II, 1% cross-reactivity with rat insulinlike growth Factor II, and no binding to insulin at 10-6 M (12).…”

Local and Systemic Expression of Insulin-like Growth Factor-I (IGF-I) mRNAs in Rat after Bone Marrow Ablation

“…Serum IGF-I radioimmunoassay was performed with monoclonal antibody 3D1/2/1 (a gift provided by Drs. R. C. Baxter and R. L. Raison and distributed by the National Hormone and Pituitary Program, the National Institute of Diabetes, Digestive and Kidney Diseases) following the procedure described (21). The levels of IGF-I were determined with multiple dilutions of serum samples each with duplicate measurements.…”