The IGFBP-5 ELISA is a quantitative two-step sandwich type immunoassay. In the first step, Calibrators, Controls and unknown diluted samples are added to IGFBP-5 antibody coated microtiter wells and incubated. After the first incubation and washing step, the wells are incubated with horseradish peroxidase labelled antibody conjugate. After a second incubation and washing step, the wells are incubated with substrate solution (TMB). After TMB incubation, an acidic stopping solution is added. In principle, the antibody-HRP conjugate binds to the solid phase antibody-antigen complex. Finally, the antibody-antigen and conjugate complex bound to the well is detected by addition of enzyme-substrate reaction. The degree of enzymatic turnover of the substrate is determined by dual wavelength absorbance measurement at 450 nm as primary test filter and 630 nm as reference filter. The absorbance measured is directly proportional to the concentration of IGFBP-5 in the samples and calibrators.

References:
1. HHS Publication, 5th ed., 2007. Biosafety in Microbiological and Biomedical Laboratories. Available http://www.cdc.gov/biosafety/publications/bmbl5/BMBL5
2. DHHS (NIOSH) Publication No. 78–127, August 1976. Current Intelligence Bulletin 13 – Explosive Azide Hazard. Available http:// www.cdc.gov/niosh.
3. Kricka L. Interferences in immunoassays – still a threat. Clin Chem 2000; 46: 1037–1038.

IGFBP-5 ELISA AL-127
Babiker A, Al Noaim K, Al Swaid A, et al. Short stature with low insulin-like growth factor 1 availability due to pregnancy-associated plasma protein A2 deficiency in a Saudi family. Clin Genet. 2021;100(5):601-606. doi: 10.1111/cge.14030.

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Bøtkjær JA, Pors SE, Petersen TS, Kristensen SG, Jeppesen JV, Oxvig C, Andersen CY. Transcription profile of the insulin-like growth factor signaling pathway during human ovarian follicular development. Assist Reprod Genet
. 2019 May;36(5):889-903. doi: 10.1007/s10815-019-01432-x. Epub 2019 Mar 15.

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DiPrisco B, Kumar A, Kalra B, Savjani GV, Michael Z, Farr O, Papathanasiou AE, Christou H, Mantzoros C. Placental proteases PAPP-A and PAPP-A2, the binding proteins they cleave (IGFBP-4 and -5), and IGF-I and IGF-II: Levels in umbilical cord blood and associations with birth weight and length. Metabolism. 2019 Nov;100:153959. doi: 10.1016/j.metabol.2019.153959. Epub 2019 Aug 8.

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Donegan D, Bale LK, Conover CA. PAPP-A in normal human mesangial cells: effect of inflammation and factors related to diabetic nephropathy. J Endocrinol. 2016 Oct;231(1):71-80. doi: 10.1530/JOE-16-0205. Epub 2016 Aug 12. PMID: 27519211.

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Heitzeneder S, Shem J, Khan J, Mackall C. Pregnancy Associated Plasma Protein A (PAPP-A) Is A Novel Therapeutic Target In Ewing Sarcoma. Presented at 8th Ovarian Cancer Research; 2016 May 15-17; Niagra Falls, ON, Canada.

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Kumar A, Kalra B, Kommareddy V, Chowdavarapu K, Mistry S, Savjani G, Oxvig C. Development of Well Characterized ELISAs for Bound and Unbound Insulin-Like Growth Factors and their Binding Proteins. Poster presented at 98th Annual Endocrine Society Meeting; 2016 Apr 1-3; Boston, MA.

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Martín-Rivada Á, Guerra Cantera S, Campillo-Calatayud A, Andrés-Esteban EM, Sánchez Holgado M, Martos-Moreno GÁ, Pozo J, Güemes M, Soriano-Guillén L, Pellicer A, Oxvig C, Frystyk J, Chowen JA, Barrios V, Argente J. Pappalysins and Stanniocalcin and Their Relationship With the Peripheral IGF Axis in Newborns and During Development. J Clin Endocrinol Metab. 2022 Sep 28;107(10):2912-2924. doi: 10.1210/clinem/dgac453. PMID: 35902207.

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Vicente Barrios, Álvaro Martín-Rivada, Gabriel Á Martos-Moreno, Sandra Canelles, Francisca Moreno-Macián, Carmen De Mingo-Alemany, Maurizio Delvecchio, Roberta Pajno, Danilo Fintini, Julie A Chowen, Jesús Argente, Increased IGFBP Proteolysis, IGF-I Bioavailability, and Pappalysin Levels in Children With Prader-Willi Syndrome, The Journal of Clinical Endocrinology & Metabolism, Volume 109, Issue 9, September 2024, Pages e1776–e1786, https://doi.org/10.1210/clinem/dgad754

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