Cardiopulmonary bypass induces leukocyte-platelet adhesion. Blood 79:1201

Cardiopulmonary bypass (CPB) has been demonstrated to activate platelets, producing an increased number of circulat-ing platelets that have undergone a-granule release and express granule membrane protein-140 (GMP-140) on their surface, In vitro, GMP-140 mediates activated platelet adhe-sion to neutrophils (PMN) and monocytes, causing the forma-tion of leukocyte-platelet conjugates. Using a newly devel-oped 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 % f 1.5 % to 44 % f 4.5 % (mean f SEM) by the end of CPB, while PMN-platelet conjugates increased only slightly and lymphocyte-platelet conjugates decreased; (2) N VITRO and in vivo activation of platelets causes I surface expressiop of the or-granule membrane protein