| abstract |
An assay for activated factor VII (factor VIIa) has been developed using truncated tissue factor (TF), a soluble mutant form of TF that retains the cofactor function of TF toward factor VIIa. Unlike full-length TF, however, tTF appears not to 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 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. |