Functional and immunologic fibrinogen assays, plasminogen, and plasmin-α₂-plasmin inhibitor complex.

Results show the time course of ancrod treatment of all 12 subjects (mean, SD, 95th percentile). (A) Fibrinogen measured as total clottable protein. (B) Fibrinogen-related antigen measured with polyclonal antiserum. (C). Plasminogen measured by chromogenic assay. (D) Plasmin-α₂-plasmin inhibitor complex measured by ELISA. Infusion of ancrod leads to a reduction in plasma fibrinogen concentration. Similar to the course of the fibrin(ogen) degradation product assays, the reduction in functional plasma fibrinogen concentration displayed a lag of 1 hour. Lowest values were observed between 8 and 15 hours after start of infusion. Fibrinogen-related antigen showed a more gradual decrease, with lowest levels after 24 hours. The discordance between functional fibrinogen levels and fibrinogen-related antigen can be explained by the presence of large amounts of fibrin(ogen) degradation products in plasma, which are not detected by the functional tests, but react with polyclonal antisera against fibrinogen. Plasminogen displays a decrease during ancrod infusion, mirrored by an increase in plasmin-α₂-plasmin inhibitor complex concentration, indicating that reduction in plasminogen is caused by plasminogen activation.