Flow Cytometric Measurement of Platelet-Leukocyte Aggregates: A Possible Target to Monitor Platelet Function?

 

 Buy Article Permissions and Reprints

ABSTRACT

Increased platelet-leukocyte-aggregate (PLA) formation has been reported in acute coronary syndromes (ACS) and during cardiopulmonary bypass, and PLA formation has been acknowledged as a possible target for antiplatelet therapy in ACS and coronary interventions. It has also been suggested as a monitoring tool for risk stratification parameters. In a controlled study design as well as under clinical conditions we investigated the effect of antiplatelet agents by flow cytometric measurement of PLA formation. We were able to demonstrate considerable reduction in PLA formation under experimental and clinical clopidogrel therapy alone or in combination with aspirin. In healthy volunteers the percentage of monocyte-PLAs decreased significantly to 55 to 75% of the baseline under clopidogrel, depending on the type and concentration of the activating agent. In patients with severe peripheral artery disease, formation of monocyte-PLAs at baseline and after stimulation with thrombin receptor activating peptide (TRAP) or adenosine diphosphate (ADP) was significantly lower under combined therapy when compared with patients under aspirin alone or without antiplatelet treatment.

Flow cytometric measurement of PLA formation appears to be well suited for dose response of antiplatelet agents in healthy volunteers and a valuable tool in establishing the clinical significance of circulating PLAs. It may also be a qualified method to monitor platelet function in long-term treatment with antiplatelet agents that interfere with the degranulation process. It is not suited for acute situations.

REFERENCES

• 1 Neumann F J, Marx N, Gawaz M et al.. Induction of cytokine expression in leukocytes by binding of thrombin-stimulated platelets.  Circulation. 1997;  95 2387-2394
  CrossrefPubMedGoogle Scholar
• 2 Ott I, Neumann F J, Gawaz M, Schmitt M, Schomig A. Increased neutrophil-platelet adhesion in patients with unstable angina.  Circulation. 1996;  94 1239-1246
  PubMedGoogle Scholar
• 3 Barry O P, Pratico D, Savani R C, FitzGerald G A. Modulation of monocyte-endothelial cell interactions by platelet microparticles.  J Clin Invest. 1998;  102 136-144
  CrossrefPubMedGoogle Scholar
• 4 Nagata K, Tsuji T, Todoroki N et al.. Activated platelets induce superoxide anion release by monocytes and neutrophils through P-selectin (CD62).  J Immunol. 1993;  151 3267-3273
  PubMedGoogle Scholar
• 5 Ross R. Atherosclerosis: an inflammatory disease.  N Engl J Med. 1999;  340 115-126
  CrossrefPubMedGoogle Scholar
• 6 Furman M I, Benoit S E, Barnard M R et al.. Increased platelet reactivity and circulating monocyte-platelet aggregates in patients with stable coronary artery disease.  J Am Coll Cardiol. 1998;  31 352-358
  CrossrefPubMedGoogle Scholar
• 7 Ott I, Neumann F J, Kenngott S, Gawaz M, Schomig A. Procoagulant inflammatory responses of monocytes after direct balloon angioplasty in acute myocardial infarction.  Am J Cardiol. 1998;  82 938-942
  CrossrefPubMedGoogle Scholar
• 8 Rinder C S, Bonan J L, Rinder H M, Mathew J, Hines R, Smith B R. Cardiopulmonary bypass induces leukocyte-platelet adhesion.  Blood. 1992;  79 1201-1205
  PubMedGoogle Scholar
• 9 Zahler S. Acute cardiac inflammatory responses to postischemic reperfusion during cardiopulmonary bypass.  Cardiovasc Res. 1999;  41 722-730
  CrossrefPubMedGoogle Scholar
• 10 Michelson A D, Barnard M R, Krueger L A, Valeri C R, Furman M I. Circulating monocyte-platelet aggregates are a more sensitive marker of in vivo platelet activation than platelet surface P-selectin: studies in baboons, human coronary intervention, and human acute myocardial infarction.  Circulation. 2001;  104 1533-1537
  CrossrefPubMedGoogle Scholar
• 11 Entman M L, Ballantyne C M. Association of neutrophils with platelet aggregates in unstable angina. Should we alter therapy?.  Circulation. 1996;  94 1206-1208
  PubMedGoogle Scholar
• 12 Furman M I, Barnard M R, Krueger L A et al.. Circulating monocyte-platelet aggregates are an early marker of acute myocardial infarction.  J Am Coll Cardiol. 2001;  38 1002-1006
  CrossrefPubMedGoogle Scholar
• 13 Sarma J, Laan C A, Alam S, Jha A, Fox K A, Dransfield I. Increased platelet binding to circulating monocytes in acute coronary syndromes.  Circulation. 2002;  105 2166-2171
  CrossrefPubMedGoogle Scholar
• 14 Neumann F J, Zohlnhofer D, Fakhoury L, Ott I, Gawaz M, Schomig A. Effect of glycoprotein IIb/IIIa receptor blockade on platelet-leukocyte interaction and surface expression of the leukocyte integrin Mac-1 in acute myocardial infarction.  J Am Coll Cardiol. 1999;  34 1420-1426
  CrossrefPubMedGoogle Scholar
• 15 May A E, Neumann F J, Gawaz M, Ott I, Walter H, Schomig A. Reduction of monocyte-platelet interaction and monocyte activation in patients receiving antiplatelet therapy after coronary stent implantation.  Eur Heart J. 1997;  18 1913-1920
  PubMedGoogle Scholar
• 16 Klinkhardt U, Graff J, Harder S. Clopidogrel but not abciximab reduces platelet leukocyte conjugates and P-selectin expression in a human ex vivo in vitro model.  Clin Pharmacol Ther. 2002;  71 176-185
  CrossrefPubMedGoogle Scholar
• 17 Klinkhardt U, Bauersachs R, Adams J, Graff J, Lindhoff-Last E, Harder S. Clopidogrel but not aspirin reduces P-selectin expression and formation of platelet-leukocyte aggregates in patients with atherosclerotic vascular disease.  Clin Pharmacol Ther. 2003;  73 232-241
  CrossrefPubMedGoogle Scholar
• 18 Phipps R P. Atherosclerosis: the emerging role of inflammation and the CD40-CD40 ligand system.  Proc Natl Acad Sci USA. 2000;  97 6930-6932
  CrossrefPubMedGoogle Scholar
• 19 Heeschen C, Dimmeler S, Hamm C W et al.. CAPTURE Study Investigators . Soluble CD40 ligand in acute coronary syndromes.  N Engl J Med. 2003;  348 1104-1111
  CrossrefPubMedGoogle Scholar

Ute KlinkhartM.D. 

Institute for Clinical Pharmacology at the Pharmazentrum Frankfurt, University Hospital Frankfurt, Theodor Stern Kai 7

D-60590 Frankfurt am Main, Germany

Email: klinkhardt@em.uni-frankfurt.de