Platelet and Monocyte Microvesicles as Potential Biomarkers of COVID-19 Severity: A Cross-Sectional Analysis

Background: Coronavirus disease (COVID-19) induces inflammation, coagulopathy following platelet and monocyte activation, and fibrinolysis, resulting in elevated D-dimer levels. Activated platelets and monocytes produce microvesicles (MVs). We analyzed the differences in platelet and monocyte MV counts in mild, moderate, and severe COVID-19, as well as their correlation with D-dimer levels. Methods: In this cross-sectional study, blood specimens were collected from 90 COVID-19 patients and analyzed for D-dimers using SYSMEX CS-2500. Platelet MVs (PMVs; PMVCD42b⁺ and PMVCD41a⁺), monocyte MVs (MMVs; MMVCD14⁺), and phosphatidylserinebinding annexin V (PS, AnnV⁺) were analyzed using a BD FACSCalibur instrument. Results: PMV and MMV counts were significantly increased in COVID-19 patients. AnnV⁺ PMVCD42b⁺ and AnnV⁺ PMVCD41a⁺ cell counts were higher in patients with severe CO-VID-19 than in those with moderate clinical symptoms. The median (range) of AnnV⁺ PMVCD42b⁺ (MV/µL) in mild, moderate, and severe COVID-19 was 1,118.3 (328.1–1,910.5), 937.4 (311.4–2,909.5), and 1,298.8 (458.2–9,703.5), respectively (P = 0.009). The median (range) for AnnV⁺ PMVCD41a⁺ (MV/µL) in mild, moderate, and severe disease was 885.5 (346.3–1,682.7), 663.5 (233.8–2,081.5), and 1,146.3 (333.3–10,296.6), respectively (P = 0.007). D-dimer levels (ng/mL) weak correlated with AnnV⁺ PMVCD41a⁺ (P = 0.047, r = 0.258). Conclusions: PMV PMVCD42b⁺ and PMVCD41a⁺ counts were significantly increased in patients with severe clinical symptoms, and PMVCD41a⁺ counts correlated with D-dimer levels. Therefore, MV counts can be used as a potential biomarker of COVID-19 severity.