title: The composition and daily variation of microparticles in whole blood in stable coronary artery disease.
abstract: BACKGROUND
  The knowledge of circadian variation of microparticles (MPs) in stable coronary artery disease (SCAD) is limited. The aim of this study was to evaluate the daily variation of platelet-, endothelial- and monocyte-derived MPs in whole blood and their tissue factor expression (TF) in SCAD and whether these MPs were related to other endothelial and coagulation markers.
  
  
  METHODS
  Serial blood samples from patients with SCAD were collected during one day. Flow cytometry was used to evaluate the amount of large MPs 0.5-1.0 μm, positive for annexin, and their expression of CD41, CD62P, CD144, CD14 and TF. The lag time and endogenous thrombin potential (ETP) was calculated by Calibrated Automated Thrombogram and soluble (s)P-selectin, sTF and vWF by ELISA.
  
  
  RESULTS
  The majority of MPs in whole blood consisted of CD41 + MPs with no significant daily variation. In contrast, the concentration of CD62P + MPs described a daily variation with the lowest concentrations found in the evening (p = 0.031). CD62P + and CD144 + MPs had the highest expression of TF, 52.6% and 42.9%, respectively, and correlated to the endothelial activity evaluated by vWF. There was a circadian rhythm of lag time (p < 0.001) and ETP (p = 0.001). The CD62P+, CD14 + and CD144 + MPs correlated to the lag time.
  
  
  CONCLUSIONS
  The different subsets of platelet-, endothelial- and monocyte-derived MPs do not present the same circadian variation and they differ in TF expression in SCAD. The MPs from activated platelets, endothelial cells and monocytes exist in low concentrations in whole blood but are related to the endothelial and coagulation activity found in SCAD.
authors.affiliation: a Department of Medical Sciences , Cardiology, Uppsala University , Uppsala , Sweden.
authors.forename: Christina
authors.initials: C
authors.lastname: Christersson
authors.affiliation: a Department of Medical Sciences , Cardiology, Uppsala University , Uppsala , Sweden.|b Department of Medical Sciences , Uppsala Clinical Research Center (UCR), Uppsala University , Uppsala , Sweden.
authors.forename: Bertil
authors.initials: B
authors.lastname: Lindahl
authors.affiliation: c Department of Medical Sciences , Clinical Chemistry, Uppsala University , Uppsala , Sweden.
authors.forename: Agneta
authors.initials: A
authors.lastname: Siegbahn
mesh_terms: D000368:Aged; D060050:Angina, Stable / Q000097:blood; D015703:Antigens, CD / Q000097:blood; D001792:Blood Platelets / Q000737:chemistry / Q000378:metabolism; D015820:Cadherins / Q000097:blood; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000737:chemistry* / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D003324:Coronary Artery Disease / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000737:chemistry / Q000378:metabolism; D019007:P-Selectin / Q000097:blood; D040201:Platelet Membrane Glycoprotein IIb / Q000097:blood; D013917:Thrombin / Q000032:analysis; D013925:Thromboplastin / Q000032:analysis; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015820:Cadherins; D019007:P-Selectin; D040201:Platelet Membrane Glycoprotein IIb; D013917:Thrombin; D013925:Thromboplastin; D000099152:Cadherin 5; C546937:SELP protein, human
keywords: Blood coagulation; coronary artery disease; microparticles; platelets; tissue factor; whole blood