title: P-selectin, tissue factor and CD40 ligand expression on platelet-leucocyte conjugates in the presence of a GPIIb/IIIa antagonist.
abstract: This study was to investigate the appearance of P-selectin, tissue factor (TF) and CD40 ligand (CD40L) on platelet-leucocyte conjugates in the absence and presence of a GPIIb/IIIa antagonist, MK-852, and the effect of adding EDTA to pre-formed conjugates. The purpose was to find out whether these antigens are displaced from the conjugates along with the platelets, thus providing information on their location. Hirudinized blood was stirred with collagen ((2 microg/mL) in the absence and presence of MK-852 (10 micromol/mL)). P-selectin, TF and CD40L were measured on platelet-leucocyte conjugates (CD42a positive monocytes and neutrophils) and on single platelets by flow cytometry. Measurements were also made after subsequent addition of EDTA (4 mmol/L). Platelet-leucocyte conjugate formation was markedly enhanced in the presence of MK-852. P-selectin, TF and CD40L expression on the conjugates was also enhanced. Monocytes bound more platelets and expressed more P-selectin, TF and CD40L than neutrophils. EDTA displaced the majority of platelets from the conjugates and also the P-selectin, TF and CD40L, whereas it did not displaced P-selectin or CD40 ligand from the platelets themselves. It is concluded that a GPIIb/IIIa antagonist promotes formation of platelet-leucocyte conjugates, which display P-selectin, TF and CD40L that appears to be associated with the adherent platelets. Platelet-monocyte conjugates are prime candidates for arterial inflammation and thrombosis. Pro-inflammatory and pro-thrombotic effects of CD40L and tissue factor may be an explanation of the negative clinical effects using GPIIb/IIIa antagonists.
authors.affiliation: Centre for Integrated Systems Biology and Medicine and Institute of Neuroscience, University of Nottingham, UK. lian.zhao@nottingham.ac.uk
authors.forename: Lian
authors.initials: L
authors.lastname: Zhao
authors.forename: Philip M W
authors.initials: PM
authors.lastname: Bath
authors.forename: Jane
authors.initials: J
authors.lastname: May
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lösche
authors.forename: Stan
authors.initials: S
authors.lastname: Heptinstall
mesh_terms: D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D023201:CD40 Ligand / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D003094:Collagen / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009000:Monocytes / Q000737:chemistry / Q000502:physiology; D009504:Neutrophils / Q000737:chemistry / Q000502:physiology; D009842:Oligopeptides / Q000494:pharmacology; D019007:P-Selectin / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000494:pharmacology; D015539:Platelet Activation; D010973:Platelet Adhesiveness / Q000187:drug effects / Q000502:physiology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000032:analysis; D053778:Thiazolidines; D013925:Thromboplastin / Q000378:metabolism*
chemical_list: D009842:Oligopeptides; D019007:P-Selectin; D010456:Peptides, Cyclic; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex; D053778:Thiazolidines; C083231:MK 0852; D023201:CD40 Ligand; D003094:Collagen; D013925:Thromboplastin; D004492:Edetic Acid