A simple quantitative assay for ristocetin cofactor activity using microtiter plate and ELISA plate reader

Area of Science:

• Hematology
• Clinical Chemistry
• Diagnostic Assays

Background:

• Ristocetin cofactor activity is essential for diagnosing von Willebrand disease.
• Current methods for its quantitative determination in clinical settings lack simplicity, speed, and precision.

Purpose of the Study:

• To develop and validate a novel, rapid, and precise quantitative assay for ristocetin cofactor activity.
• To establish an ELISA-based method suitable for routine clinical laboratory use.

Main Methods:

• An enzyme-linked immunosorbent assay (ELISA) was developed using paraformaldehyde-fixed platelets, plasma samples, and ristocetin in microtiter plates.
• Platelet agglutination was measured via light absorbance at 405 nm.
• A standard curve was constructed using serial dilutions of normal pooled plasma, and results were compared to aggregometer assays.

Main Results:

• The new ELISA method demonstrated a significant linear correlation with traditional aggregometer assays (p < 0.0001).
• Intra-assay variation was 6%, and inter-assay variation was 17%, indicating good reproducibility.
• The assay provides precise quantitation of plasma ristocetin cofactor activity.

Conclusions:

• The developed ELISA assay offers a simple, rapid, and precise method for quantifying ristocetin cofactor activity.
• This assay is a valuable tool for the diagnosis and management of von Willebrand disease in clinical laboratories.