Fig. 1. Flow-cytometric detection of MVs. (A) The MV gate region was separated, defined, and calculated using the SSC-height (log) scale as the threshold to eliminate the 0.16-µm beads and use the 0.2- and 0.5-µm bead clouds to set the MV gate. The gate used for capturing the beads for counting is depicted as region 1 (R1). (B) MVs were calibrated using Megamix-Plus SSC beads in a Trucount tube, using fluorescence (FL1)/FITC as the threshold. (C) FSC and SSC of isolated MVs stained with fluorescence (FL), fluorescein isothiocyanate (FITC)-conjugated CD42b, and Trucount calibrator beads (R1). (D) Analysis of a specimen from a COVID-19 patient using a Trucount tube to obtain the R4 region. R4 comprised Trucount gating beads for counting. (E) MV-negative control, analyzed from healthy controls without staining with fluorescent-labeled antibodies (unstained). (F) The MV population of healthy controls with annexin V-positive staining was analyzed for PMVs (AnnV⁺ PMVCD42b⁺, AnnV⁺ PMVCD41a⁺) and MMVs (AnnV⁺ MMVCD14⁺). (G) The MV population of mild COVID-19 patients with annexin V-positive staining was analyzed for PMVs and MMVs. (H) The MV population of moderate COVID-19 patients with annexin V-positive staining was analyzed for PMVs and MMVs. (I) The MV population of severe COVID-19 patients with annexin V-positive staining was analyzed for PMVs and MMVs. The detected MVs were conjugated with fluorescent FITC for CD42b, PerCP-Cy5.5 for CD41a, APC for CD14, and PE for annexin V.
Abbreviations: MVs, microvesicles; PMVs, platelet microvesicles; MMVs, monocyte microvesicles; Qty, quantity; FSC, forward scatter; SSC, side scatter; FITC, fluorescein isothiocyanate; PerCP-Cy5.5, peridinin chlorophyll protein-cyanine5.5; APC, allophycocyanin; PE, phycoerythrin.

Ann Lab Med 2024;44:392~400 https://doi.org/10.3343/alm.2023.0395