Review
作者: Chareyre, Corinne  ; Camera, Marina  ; de Menezes, Erika Marques  ; Featherby, Sophie  ; Nybo, Jette  ; Franco, Corentin  ; Burrello, Jacopo  ; Brambilla, Marta  ; Aharon, Anat  ; Kristensen, Soren Risom  ; Wahlund, Casper  ; Hisada, Yohei  ; Orbe, Josune  ; Langer, Florian  ; Hogwood, John  ; Badimon, Lina  ; Lacroix, Romaric  ; Lucien, Fabrice  ; Suades, Rosa  ; Bouriche, Tarik  ; Snir, Omri  ; Hau, Chi  ; Beckmann, Lennart  ; Bonifay, Amandine  ; Roncal, Carmen  ; Bolis, Sara  ; Martinod, Kimberly  ; Campello, Elena  ; Gray, Elaine  ; Paramo, Jose A  ; Norris, Philip  ; Benedikter, Birke  ; Mullier, François  ; Abdili, Evelyne  ; Samadi, Nazanin  ; Baudar, Justine  ; Radu, Claudia M  ; Nieuwland, Rienk  ; Judicone, Coralie  ; Dignat-George, Françoise  ; Kim, Yohan  ; Sachetto, Ana Teresa Azevedo  ; Thaler, Johannes  ; Faille, Dorothée  ; Latysheva, Nadezhda  ; Osterud, Bjarne  ; Mackman, Nigel  ; Laakmann, Katrin  ; Barile, Lucio  ; Ettelaie, Camille  ; Guldenpfennig, Maite  ; Hansen, John-Bjarne 
BACKGROUNDScientific and clinical interest in extracellular vesicles (EVs) is growing. EVs that expose tissue factor (TF) bind factor VII/VIIa and can trigger coagulation. Highly procoagulant TF-exposing EVs are detectable in the circulation in various diseases, such as sepsis, COVID-19, or cancer. Many in-house and commercially available assays have been developed to measure EV-TF activity and antigen, but only a few studies have compared some of these assays.OBJECTIVESThe International Society on Thrombosis and Haemostasis Scientific and Standardization Committee Subcommittee on Vascular Biology initiated a multicenter study to compare the sensitivity, specificity, and reproducibility of these assays.METHODSPlatelet-depleted plasma samples were prepared from blood of healthy donors. The plasma samples were spiked either with EVs from human milk or EVs from TF-positive and TF-negative cell lines. Plasma was also prepared from whole human blood with or without lipopolysaccharide stimulation. Twenty-one laboratories measured EV-TF activity and antigen in the prepared samples using their own assays representing 18 functional and 9 antigenic assays.RESULTSThere was a large variability in the absolute values for the different EV-TF activity and antigen assays. Activity assays had higher specificity and sensitivity compared with antigen assays. In addition, there was a large intra-assay and interassay variability. Functional assays that used a blocking anti-TF antibody or immunocapture were the most specific and sensitive. Activity assays that used immunocapture had a lower coefficient of variation compared with assays that isolated EVs by high-speed centrifugation.CONCLUSIONBased on this multicenter study, we recommend measuring EV-TF using a functional assay in the presence of an anti-TF antibody.