Not All TF Activity Assays Measure Tissue Factor – RPTH Journal
RPTH Journal shared a post on LinkedIn about a recent article by Ana T.A. Sachetto et al, adding:
“Measuring tissue factor activity in plasma sounds straightforward.
In reality, it’s anything but!
TF-positive extracellular vesicles are increasingly linked to thrombosis, cancer, sepsis, and inflammatory disease, but accurately detecting low circulating TF activity remains a major technical challenge.
A new RPTH methodological study systematically evaluated 3 commercial plasma TF activity assays against the well-established Chapel Hill EV TF activity assay.
What did they find?
All 3 kits detected recombinant TF (Innovin)
- But sensitivity and specificity varied substantially
- Plasma background absorbance and hemolysis interfered with measurements
- Some assays detected large amounts of TF-independent activity
- Plasma clotting occurred in certain assay systems
The strongest performer?
The Chapel Hill EV TF activity assay remained the most sensitive and specific approach for detecting TF-dependent activity.
Compared with commercial assays, fold increase in LPS-stimulated samples vs controls:
- Chapel Hill assay: 33-fold
- Abcam: 11-fold
- AssaySense: 5-fold
One important message from this paper:
Not all ‘TF activity’ measurements actually reflect tissue factor. Without proper controls, plasma background, EV-independent coagulation activity, and optical interference can all distort interpretation.
A valuable technical contribution for anyone studying extracellular vesicles, coagulation, immunothrombosis, or plasma biomarkers.”
Title: Evaluation of 3 commercial assays for the measurement of tissue factor activity in human plasma
Authors: Ana T.A. Sachetto, Dougald M. Monroe, Nigel Mackman

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