A radioimmunoassay for protein C

Area of Science:

• Biochemistry
• Immunology
• Clinical Chemistry

Background:

• Protein C is a crucial vitamin K-dependent plasma protein involved in regulating blood coagulation.
• Accurate measurement of protein C levels is essential for diagnosing and managing thrombotic disorders and monitoring anticoagulant therapy.
• Existing methods for protein C quantification may have limitations in terms of simplicity, reliability, or cost.

Purpose of the Study:

• To develop and validate a simple and dependable radioimmunoassay (RIA) for quantifying protein C in human plasma.
• To establish reference ranges for protein C concentration in healthy individuals.
• To assess the impact of warfarin therapy and hereditary protein C deficiency on plasma protein C levels.

Main Methods:

• Affinity purification of rabbit anti-human protein C antibodies, specifically targeting the activation peptide region (residues 1-15) of the heavy chain.
• Development of a radioimmunoassay using the affinity-purified antibodies and a radiolabeled peptide tracer.
• Measurement of protein C concentrations in plasma samples from healthy subjects, warfarin-treated individuals, and patients with hereditary protein C deficiency.

Main Results:

• The developed radioimmunoassay demonstrated simplicity and dependability for protein C measurement.
• Normal protein C concentration in healthy subjects was determined to be 2.5 +/- 0.9 mg/l (2 SD).
• Warfarin treatment resulted in a significant reduction of protein C levels to approximately 40% of normal values.
• Patients with hereditary protein C deficiency exhibited markedly reduced protein C levels, ranging from 0.5 mg/l to 1.6 mg/l.

Conclusions:

• The established radioimmunoassay provides a reliable method for determining plasma protein C levels.
• The assay is capable of differentiating between normal individuals, individuals on warfarin therapy, and those with hereditary protein C deficiency.
• This assay facilitates the clinical assessment of protein C status and aids in the diagnosis of related hemostatic abnormalities.