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Optimized flow cytometric assay for the measurement of platelet microparticles in plasma: pre-analytic and analytic
1Hematologic Malignancies Branch, Division of Special Cancers, National Cancer Center, Goyang, Gyeonggi, Korea. lukekhk@ncc.re.kr
Abstract:
Platelet microparticles (PMP) are submicroscopic membrane vesicles released by platelets during activation. Flow cytometry is the most widely used method for quantifying PMP, but the optimization of the technical method has not yet been fully evaluated. This study was designed to assess the pre-analytical variables including blood sampling conditions, and to evaluate the analytical variations including effect of the platelet-specific antibodies and quantitative beads, precision, linearity and accuracy in comparison with beta-thromboglobulin, which is one of the platelet activation markers. Numbers of PMP collected into citrate-theophylline-adenosine-dipyridamole (CTAD) tubes were increased with time, but to a lesser extent than when collected into sodium citrate tubes. The precision of the PMP assay was relatively high. Excellent linear correlation was observed for dilution linearity. Regarding the platelet-specific antibodies used, anti-CD41a-labeled samples resulted in higher PMP levels than those labeled with anti-CD61 and anti-CD42a. There was no significant difference of PMP counts according to the quantitative beads. The PMP assay is well correlated with beta-thromboglobulin levels. Our findings suggest that blood samples for the PMP assay should be collected in a CTAD tube and delayed measurement is not allowed to avoid artefactual platelet activation. The PMP assay can be used successfully as a useful marker of the detection of in vivo platelet activation, provided that pre-analytical and technical points are optimally taken into consideration.
Insights
Optimizing platelet microparticle (PMP) quantification is crucial. Blood collection in CTAD tubes and prompt analysis minimize artefactual activation, ensuring PMP assays accurately reflect in vivo platelet activation.
Area of Science:
- Hematology
- Biotechnology
- Analytical Chemistry
Background:
- Platelet microparticles (PMP) are vesicles released during platelet activation.
- Flow cytometry is standard for PMP quantification, but method optimization requires evaluation.
- Standardization is needed for reliable PMP measurement as a biomarker.
Purpose of the Study:
- To assess pre-analytical variables (e.g., blood sampling) for PMP quantification.
- To evaluate analytical variations, including antibody effects, precision, linearity, and accuracy.
- To compare PMP assay results with beta-thromboglobulin, a platelet activation marker.
Main Methods:
- Investigated blood collection tubes (CTAD vs. sodium citrate) and time-dependent PMP changes.
- Assessed effects of platelet-specific antibodies (CD41a, CD61, CD42a) and quantitative beads.
- Evaluated assay precision, linearity, and accuracy against beta-thromboglobulin.
Main Results:
- PMP levels increased over time in both CTAD and sodium citrate tubes, but less so in CTAD.
- The PMP assay demonstrated high precision and excellent dilution linearity.
- Anti-CD41a antibody yielded higher PMP levels compared to anti-CD61 and anti-CD42a; quantitative beads showed no significant difference.
Conclusions:
- Blood collection in CTAD tubes and prompt analysis are recommended to prevent artefactual platelet activation.
- The PMP assay is a reliable marker for in vivo platelet activation when pre-analytical and analytical factors are optimized.
- Careful consideration of technical details ensures accurate PMP quantification.