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.
Rinder
C S
CS
Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510.
Bonan
J L
JL
Rinder
H M
HM
Mathew
J
J
Hines
R
R
Smith
B R
BR
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