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DOI: 10.1160/TH07-01-0025
Identification of tissue factor and platelet-derived particles on leukocytes during cardiopulmonary bypass by flow cytometry and immunoelectron microscopy
Publication History
Received
15 January 2007
Accepted after resubmission
26 April 2007
Publication Date:
28 November 2017 (online)


Summary
The extrinsic coagulation system initiated by tissue factor (TF) appears to be a major procoagulant stimulus during cardiopulmonary bypass (CPB), although the precise mechanisms remain to be revealed.We recently reported the appearance ofTF-bearing leukocytes during CPB and described their role in promoting coagulation. In this study, we visually identified the in-vivo appearance ofTF-bearing leukocytes and platelet-derived particles on leukocytes in the pericardial blood during cardiac surgery with CPB, by flow cytometry and immunoelectron microscopy. Preliminary flow cytometric experiments showed that the proportion of TF-positive or both TF- and platelet antigen CD41a-positive leukocytes was increased markedly in pericardial blood obtained during CPB,compared with the proportions in preoperative circulating blood. Immunoelectron microscopic analysis revealed that both monocytes and polymorphonuclear leukocytes in the pericardial blood express TF. On the surfaces of these cells, CD41a-positive or both CD41a- and TF-positive platelet-derived particles were observed. Platelet-derived particles include not only microparticles, but also platelets themselves. Leukocytes from preoperative circulating blood contained far fewer of these particles. Our results demonstrate the in-vivo appearance of TF-bearing platelet-derived particles on leukocytes during cardiac surgery with CPB.These findings may be important for the development of strategies to control procoagulant activities during and after cardiac surgery.