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Not All TF Activity Assays Measure Tissue Factor – RPTH Journal
May 8, 2026, 19:15

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

RPTH Journal

Other articles about RPTH Journal on Hemostasis Today.