Calibrated kallikrein generation in human plasma

Area of Science:

• Biochemistry
• Hematology

Background:

• The physiological role of the contact system is not fully understood.
• Deficiencies in factor XII (FXII), prekallikrein (PK), or high molecular weight kininogen do not cause obvious clinical issues, despite the system's in vitro links to coagulation, fibrinolysis, and inflammation.

Purpose of the Study:

• To develop a global generation assay for the initial phase of the contact system.
• To create a valuable tool for investigating the contact system's physiological role.

Main Methods:

• Investigated developing a method based on the Calibrated Automated Thrombin generation principle.
• Identified a kallikrein-specific fluorogenic substrate and measured kallikrein generation in plasma activated by silica.
• Corrected for signal-affecting issues like substrate depletion and inner-filter effect using external calibration.

Main Results:

• Kallikrein generation was successfully measured in undiluted plasma.
• External calibration with α2-macroglobulin-kallikrein complexes addressed signal interferences.
• Studies confirmed the signal primarily reflects FXII-dependent kallikrein activity.

Conclusions:

• Established a viable method for measuring kallikrein generation.
• This assay has potential for clinical studies of the contact system.