Noncompetitive ELISA for human serum insulin-like growth factor-I

M. J. Khosravi, A. Diamandi, J. Mistry, Phillip Lee

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Measurement of serum insulin-like growth factor I (IGF-I) is important in assessing the growth hormone/IGF axis. Competitive immunoassay methods for IGF-I are complicated by substantial interference from IGF-binding proteins (IGFBPs) due to the relatively low ratio of specific antibody to IGFBPs in the sample, even after standard acid-ethanol sample extraction. We report the development of a noncompetitive ELISA for human IGF-I that avoids this problem by utilizing excess amounts of capture and detection antibodies. Serum samples were prepared by using an abbreviated acid-ethanol extraction method. Neutralized supernatant was added to microwells coated with IGF-I capture antibody; horseradish peroxidase-labeled detection antibody was then added, incubated for 2 h, and then developed. Compared with the 'gold standard' method of acid-column chromatography, the simplified acid-ethanol extraction yields a mean ± SD recovery of 103% ± 5.5% despite the presence of residual IGFBPs in the extracted sample. Comparisons with a centrifugal filtration sample extraction method are also shown. The ELISA is specific for IGF-I with an absolute sensitivity of 0.03 μg/L and inter- and intraassay CVs of 3.9-8.8% and 2.66.7%, respectively. The availability of a rapid IGF-I ELISA combined with a simple and reliable sample preparation procedure should facilitate clinical and research studies of this important growth factor.

Original languageEnglish (US)
Pages (from-to)1147-1154
Number of pages8
JournalClinical Chemistry
Volume42
Issue number8
StatePublished - 1996
Externally publishedYes

Fingerprint

Insulin-Like Growth Factor I
Enzyme-Linked Immunosorbent Assay
Insulin-Like Growth Factor Binding Proteins
Serum
Acids
Ethanol
Antibodies
Column chromatography
Horseradish Peroxidase
Immunoassay
Growth Hormone
Chromatography
Intercellular Signaling Peptides and Proteins
Availability
Recovery
Research

Keywords

  • acid-ethanol extraction
  • growth hormone
  • immunoassay
  • insulin-like growth factor-binding protein

ASJC Scopus subject areas

  • Clinical Biochemistry

Cite this

Khosravi, M. J., Diamandi, A., Mistry, J., & Lee, P. (1996). Noncompetitive ELISA for human serum insulin-like growth factor-I. Clinical Chemistry, 42(8), 1147-1154.

Noncompetitive ELISA for human serum insulin-like growth factor-I. / Khosravi, M. J.; Diamandi, A.; Mistry, J.; Lee, Phillip.

In: Clinical Chemistry, Vol. 42, No. 8, 1996, p. 1147-1154.

Research output: Contribution to journalArticle

Khosravi, MJ, Diamandi, A, Mistry, J & Lee, P 1996, 'Noncompetitive ELISA for human serum insulin-like growth factor-I', Clinical Chemistry, vol. 42, no. 8, pp. 1147-1154.
Khosravi MJ, Diamandi A, Mistry J, Lee P. Noncompetitive ELISA for human serum insulin-like growth factor-I. Clinical Chemistry. 1996;42(8):1147-1154.
Khosravi, M. J. ; Diamandi, A. ; Mistry, J. ; Lee, Phillip. / Noncompetitive ELISA for human serum insulin-like growth factor-I. In: Clinical Chemistry. 1996 ; Vol. 42, No. 8. pp. 1147-1154.
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