Tissue Factor Activity Assay in Plasma

Plasma TF procoagulant activity was measured using the Tissue Factor Human Chromogenic Activity Assay Kit (ABCAM, #ab108906) as previously described (26 (link)). Briefly, 10 µL plasma was added to assay mix comprising of 50 µL assay diluent, 10 µL factor VII and 10 µL factor X and mixed. The mixed sample was incubated at 37°C for 30 minutes and subsequently 20 µL FXa substrate was added to the sample. Absorbance at 405 nm was measured every 5 minutes for 35 minutes with a microplate reader. Standard curves were prepared by serially diluting standard solution (500pM) 1:2 with sample diluent which correlated with TF activity.