Low levels of tissue factor-positive extracellular vesicles are present in plasma from patients with different diseases. However, most antigen-based assays, including ELISA and flow cytometry, do not have the sensitivity to detect these low levels. Numerous papers have employed ELISA or flow cytometry to detect tissue factor in plasma.
Our protocol measures tissue factor activity in plasma with high sensitivity and specificity, although there is some variability due to the use of a functional assay. There are commercial assay kits that measure levels of tissue factor activity in plasma. However, these kits do not contain anti-tissue factor antibodies, and therefore cannot distinguish between tissue factor-dependent and tissue factor-independent Factor X generation.
