CC-BY 4.0 · TH Open 2018; 02(02): e147-e157
DOI: 10.1055/s-0038-1642021
Original Article
Georg Thieme Verlag KG Stuttgart · New York

Postprandial Increase in Blood Plasma Levels of Tissue Factor–Bearing (and Other) Microvesicles Measured by Flow Cytometry: Fact or Artifact?

Morten Mørk
Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
Aalborg AF Study Group, Aalborg University Hospital, Aalborg, Denmark
EVsearch.dk, Aalborg, Denmark
,
Morten H. Nielsen
Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
EVsearch.dk, Aalborg, Denmark
,
Rikke Bæk
EVsearch.dk, Aalborg, Denmark
Department of Clinical Immunology, Aalborg University Hospital, Aalborg, Denmark
,
Malene M. Jørgensen
EVsearch.dk, Aalborg, Denmark
Department of Clinical Immunology, Aalborg University Hospital, Aalborg, Denmark
,
Shona Pedersen
Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
EVsearch.dk, Aalborg, Denmark
Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
,
Søren R. Kristensen
Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
Aalborg AF Study Group, Aalborg University Hospital, Aalborg, Denmark
EVsearch.dk, Aalborg, Denmark
Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
› Author Affiliations
Funding The study was supported by research grants from the Danish Council for Strategic Research.
Further Information

Publication History

15 November 2017

01 March 2018

Publication Date:
16 April 2018 (online)

Abstract

Tissue factor (TF)–bearing microvesicles (MVs) and exosomes may play a role in hemostasis and thrombosis. MVs may be quantified by flow cytometry (FC)–based detection of phosphatidylserine (PS)-positive submicron particles carrying specific antigens, although interference from lipoproteins complicates this approach. In this study, we evaluated the effect of food intake on blood levels of TF-bearing particles measured by FC and small extracellular vesicles (EVs) measured by a protein microarray–based test termed EV Array. Platelet-free plasma (PFP) was obtained from 20 healthy persons in the fasting state and 75 minutes after consumption of a meal. Postprandial changes in the concentration of PS-positive particles, including subgroups binding labeled antibodies against TF, CD41, CD146, and CD62E, respectively (FC), small EVs (EV Array), and TF antigen and procoagulant phospholipids (PPLs) were measured. Furthermore, we tested the effect on FC results of in vitro addition of lipoproteins to fasting PFP. We found significantly increased plasma concentrations of PS-positive particles and all examined subgroups postprandially, while no changes in small EVs, PPL, or TF antigen levels were found. Levels of all types of particles measured by FC were also elevated by lipoprotein spiking. In conclusion, meal consumption as well as in vitro addition of lipoproteins to fasting plasma induces increased levels of PS-positive particles as measured by FC, including TF-positive subtypes and subtypes exposing other antigens. While the observed postprandial increase may to some extent reflect elevated MV levels, our results indicate a substantial interference from lipoproteins.