Cardiopulmonary bypass induces leukocyte-platelet adhesion.
Cardiopulmonary bypass (CPB) has been demonstrated to activate platelets, producing an increased number of circulating platelets that have undergone alpha-granule release and express granule membrane protein-140 (GMP-140) on their surface. In vitro, GMP-140 mediates activated platelet adhesion to neutrophils (PMN) and monocytes, causing the formation of leukocyte-platelet conjugates. Using a newly developed assay that measures the percentage of circulating leukocyte-platelet conjugates in whole blood, we studied 17 patients undergoing CPB and have determined that (1) monocyte-platelet conjugates increased significantly during CPB, from 18% +/- 1.5% to 44% +/- 4.5% (mean +/- SEM) by the end of CPB, while PMN-platelet conjugates increased only slightly and lymphocyte-platelet conjugates decreased; (2) the time course of the increase in monocyte- and PMN-platelet conjugates paralleled that of the increase in circulating activated platelets, as determined by the presence of surface GMP-140; and (3) monocyte activation, as assessed by increased surface expression of CD11b, showed a gradual increase similar to the increase in monocyte-platelet conjugates, while PMN surface CD11b peaked immediately after the start of CPB. We conclude that CPB, through increased platelet GMP-140 expression, causes formation of monocyte-platelet, and to a lesser extent, PMN-platelet conjugates. The activation of monocytes and PMN on CPB, as evidenced by CD11b expression, occurs with differing time courses.
Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510.
C S
CS
Rinder
J L
JL
Bonan
H M
HM
Rinder
J
J
Mathew
R
R
Hines
B R
BR
Smith
D001792:Blood Platelets / Q000737:chemistry / Q000502:physiology*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D002448:Cell Adhesion; D006801:Humans; D007700:Kinetics; D007962:Leukocytes / Q000737:chemistry / Q000502:physiology*; D016177:Macrophage-1 Antigen / Q000032:analysis; D009000:Monocytes / Q000502:physiology; D009504:Neutrophils / Q000502:physiology; D019007:P-Selectin; D015539:Platelet Activation; D010980:Platelet Membrane Glycoproteins / Q000032:analysis
D016177:Macrophage-1 Antigen; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins