Red cell microparticle enumeration: validation of a flow cytometric approach

Area of Science:

• Hematology
• Biotechnology
• Analytical Chemistry

Background:

• Red blood cell microparticles (RBC-MPs) are implicated in transfusion reactions and sickle cell disease.
• Current methods for enumerating RBC-MPs lack standardization and internal validation.
• Accurate RBC-MP quantification is crucial for understanding their role in coagulation and inflammation.

Purpose of the Study:

• To present and validate a novel flow cytometric approach for enumerating RBC-MPs.
• To introduce an internal standard for improving the precision and reliability of RBC-MP counts.
• To establish a standardized method for RBC-MP analysis in clinical and research settings.

Main Methods:

• Enumeration of Glycophorin A(+) Annexin V(+) events from isolated RBC microparticles (MPs).
• Utilized a mixture of absolute counting beads (7.6 μm) and calibration beads (0.5, 0.9, 3 μm) as an internal standard.
• Validated precision using the ratio of 7.6:3-μm bead events across samples.

Main Results:

• The 0.5- and 0.9-μm beads helped define the light scatter distribution of MPs.
• The internal standard (7.6:3-μm bead ratio) demonstrated high precision (CV 2.5-7.2%) across samples.
• RBC MP counts increased with ionophore and calcium stimulation, with higher counts in platelet-rich plasma.

Conclusions:

• The developed flow cytometry method provides a validated strategy for RBC-MP enumeration.
• Reliable discrimination of calibration bead sizes by the flow cytometer is essential for method accuracy.
• This approach enhances the precision of RBC-MP detection in various biological samples.