BACKGROUND:Nuclear factor kappa B (NF-kappa B) activation and tissue factor (TF) expression may contribute to lethality in sepsis. Inappropriate in vivo expression of TF is likely responsible for fibrin deposition in sepsis-associated disseminated intravascular coagulation (DIC). Clinical assessment of TF expression has remained a major challenge. No point-of-care assays are currently available to measure the level of TF activity in whole blood. The current study examined the suitability of the TiFaCT assay as a point-of-care assay to detect TF expression. METHODS:30 healthy male volunteers received2 ng/kg of LPS. Tissue factor-dependent coagulation was quantified with a novel assay called tissue factor clotting time (TiFaCT), and by measurement of activation markers of downstream coagulation. RESULTS: Ex vivo addition of anti-TF antibodies to blood slightly increased clotting times at 0-24 h (p<0.01) indicating that some tissue factor activity was present in whole blood at any time. LPS bolus infusion decreased TiFaCT clotting time by -23% compared to baseline (p<0.01), when in vivo clotting increased, as demonstrated by a 10-fold increase in prothrombin fragment levels (F1+2). Ex vivo incubation with LPS considerably shortened TiFaCT (from 1000s to 400s as compared to control incubation; p<0.01). This effect was blunted at 2-4 h after LPS infusion (i.e. the time of monocytopenia), but twofold enhanced 24 h after LPS challenge (p<0.01). CONCLUSIONS: In summary, the TiFaCT assay was validated in our in vivo model of LPS-induced coagulation. It detected minute quantities of circulating TF even at baseline. TiFaCT is shortened at times of in vivo thrombin generation.
RCT Entities:
BACKGROUND:Nuclear factor kappa B (NF-kappa B) activation and tissue factor (TF) expression may contribute to lethality in sepsis. Inappropriate in vivo expression of TF is likely responsible for fibrin deposition in sepsis-associated disseminated intravascular coagulation (DIC). Clinical assessment of TF expression has remained a major challenge. No point-of-care assays are currently available to measure the level of TF activity in whole blood. The current study examined the suitability of the TiFaCT assay as a point-of-care assay to detect TF expression. METHODS: 30 healthy male volunteers received 2 ng/kg of LPS. Tissue factor-dependent coagulation was quantified with a novel assay called tissue factor clotting time (TiFaCT), and by measurement of activation markers of downstream coagulation. RESULTS: Ex vivo addition of anti-TF antibodies to blood slightly increased clotting times at 0-24 h (p<0.01) indicating that some tissue factor activity was present in whole blood at any time. LPS bolus infusion decreased TiFaCT clotting time by -23% compared to baseline (p<0.01), when in vivo clotting increased, as demonstrated by a 10-fold increase in prothrombin fragment levels (F1+2). Ex vivo incubation with LPS considerably shortened TiFaCT (from 1000s to 400s as compared to control incubation; p<0.01). This effect was blunted at 2-4 h after LPS infusion (i.e. the time of monocytopenia), but twofold enhanced 24 h after LPS challenge (p<0.01). CONCLUSIONS: In summary, the TiFaCT assay was validated in our in vivo model of LPS-induced coagulation. It detected minute quantities of circulating TF even at baseline. TiFaCT is shortened at times of in vivo thrombin generation.