UNC Blood Research Center, Division of Hematology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, USA.
Curr Opin Hematol. 2022 Sep 1;29(5):266-274. doi: 10.1097/MOH.0000000000000730. Epub 2022 Jul 11.
This review evaluates the different methods used to measure levels of tissue factor (TF) in plasma and on extracellular vesicles (EVs). Levels of TF-positive (TF+) EVs in blood are increased in a variety of diseases, such as cancer, sepsis, and viral infection, and are associated with thrombosis. Highly sensitive assays are required to measure the low levels of TF+ EVs in blood.
TF antigen levels in plasma have been measured using standard ELISAs, SimpleStep ELISA technology, and solid-phase proximity ligation assay. Some studies reported the detection of TF+ EVs in plasma by flow cytometry. In addition, TF+ EVs can be captured onto beads and chips using anti-TF antibodies. Several assays have been developed to measure TF activity in EVs isolated from plasma. Importantly, activity-based assays are more sensitive than antigen-based assays as a single TF/FVIIa complex can generate large amounts of FXa.
We recommend isolating EVs from plasma and measuring TF activity using a functional assay in the presence and absence of an anti-TF antibody. We do not recommend using antigen-based assays as these are not sensitive enough to detect the low levels of TF in plasma.
本综述评估了用于测量血浆中和细胞外囊泡（EVs）中组织因子（TF）水平的不同方法。在各种疾病（如癌症、脓毒症和病毒感染）中，血液中 TF 阳性（TF+）EVs 的水平升高，并与血栓形成有关。需要高灵敏度的检测方法来测量血液中低水平的 TF+EVs。
使用标准 ELISA、SimpleStep ELISA 技术和固相邻近连接测定法测量血浆中的 TF 抗原水平。一些研究报告通过流式细胞术检测到血浆中的 TF+EVs。此外，可使用抗 TF 抗体将 TF+EVs 捕获到珠子和芯片上。已经开发了几种测定法来测量从血浆中分离的 EVs 中的 TF 活性。重要的是，基于活性的测定比基于抗原的测定更灵敏，因为单个 TF/FVIIa 复合物可以产生大量的 FXa。
我们建议从血浆中分离 EVs，并在存在和不存在抗 TF 抗体的情况下使用功能测定法测量 TF 活性。我们不建议使用基于抗原的测定法，因为这些方法不够灵敏，无法检测到血浆中低水平的 TF。
