An enzyme linked immunosorption assay for tissue factor pathway inhibitor.
An assay for the quantification of full-length and carboxy-terminus truncated tissue factor pathway inhibitor (TFPI) has been developed. The assay is a classical two-antibody sandwich assay with a monoclonal capture antibody directed against the third Kunitz-type domain of human TFPI and a polyclonal rabbit peroxidase-labelled anti-human TFPI detecting antibody. The assay is sensitive to full-length and carboxy-terminus truncated TFPI with intact third Kunitz-type domain, but not to two-domain TFPI. TFPI associated with lipoproteins is not or only sparsely detected and TFPI in complex with factor Xa only partially measured. The assays gives linear reference curves in the dose range of 5 to 100 ng/ml in a double logarithmic plot. The normal range assessed from analyses on citrated plasma from 81 normal human donors is 7.8 to 26.0 ng/ml (average +/- 2 SD, log-normal distribution). There is no statistically significant difference between TFPI levels measured in 10 fasting and 10 non-fasting individuals. The reproducibility of the assay is about 5.6-5.9% (relative standard error) and the within-days and between-day reproducibilities are 4.7-5.1% and 5.9-8.5%, respectively. The assay is in very good agreement with a commercial ELISA assay recently marketed. A robust, reproducible and convenient ELISA assay for the determination of full-length and three-domain TFPI has been developed.
Ostergaard
P B
PB
Novo Nordisk A/S, Bagsvaerd, Denmark.
Beck
T C
TC
Orsted
H
H
Svendsen
A
A
Nordfang
O
O
Sandset
P M
PM
Hansen
J B
JB
D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D065427:Factor Xa Inhibitors; D005343:Fibrinolytic Agents / Q000097:blood*; D006801:Humans; D008074:Lipoproteins / Q000097:blood*; D011817:Rabbits; D011933:Reagent Kits, Diagnostic; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D065427:Factor Xa Inhibitors; D005343:Fibrinolytic Agents; D008074:Lipoproteins; D011933:Reagent Kits, Diagnostic; C051928:lipoprotein-associated coagulation inhibitor