摘要 |
An kit for an assay for measuring activated factor VII (factor VIIa) is disclosed which employs a reagent comprising truncated tissue factor (tTF), a soluble mutant form of tissue factor (TF) that retains the cofactor function of TF toward factor VIIa, but does not support the conversion of factor VII to VIIa. As a result, the tTF assay for factor VIIa is free from interference from factor VII in the plasma and is therefore specific for factor VIIa. The assay is much simpler than existing assays, because it is a single-stage clotting assay performed almost identically to a prothrombin time (PT) assay. It is also considerably more sensitive than current assays for factor VIIa in plasma. Since the tTF assay is calibrated against a factor VIIa standard, it yields an absolute concentration of factor VIIa in ng/ml. |