Non-competitive time-resolved immunofluorometric assays for determination of human insulin-like growth factor I and II.
We present sensitive non-competitive time-resolved immunofluorometric assays (TR-IFMAs) for IGF-I and IGF-II based on monoclonal antibodies. Assays were performed in microtest-plate wells: the first antibodies were immobilized on the solid matrix, the second labelled with the chelate derivative of Europium (Eu3+). The obtained specificities and sensitivities were high: IGF-I and IGF-II cross-reactivity in heterologous assay was below 0.0002%. The detection limits were 0.0025 micrograms/l and 0.010 micrograms/l for the IGF-I and IGF-II assay, respectively. The operating range included upwards: 2.5 micrograms/l (IGF-I) and 10.0 micrograms/l (IGF-II). This implies that all clinically relevant serum concentrations could be measured in one final dilution (1:1066 for IGF-I and 1:2132 for IGF-II) after acid ethanol extraction. The high sample dilution with buffer made further neutralization or evaporation of serum acid ethanol extracts unnecessary. Interassay variation of the assays was below 10%.
Frystyk
J
J
Medical Research Laboratories, Aarhus University Hospital, Denmark.
Dinesen
B
B
Orskov
H
H
D000172:Acromegaly / Q000097:blood*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000911:Antibodies, Monoclonal; D002648:Child; D002675:Child, Preschool; D002850:Chromatography, Gel; D005455:Fluorescent Antibody Technique; D013006:Growth Hormone / Q000172:deficiency*; D006801:Humans; D007202:Indicators and Reagents; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007335:Insulin-Like Growth Factor II / Q000032:analysis*; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; D007202:Indicators and Reagents; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone