N. Faraday et al., Leukocytes can enhance platelet-mediated aggregation and thromboxane release via interaction of P-selection glycoprotein ligand 1 with P-selectin, ANESTHESIOL, 94(1), 2001, pp. 145-151
Citations number
35
Categorie Soggetti
Aneshtesia & Intensive Care","Medical Research Diagnosis & Treatment
Background: Platelet-leukocyte conjugates have been observed in patients wi
th unstable coronary syndromes and after cardiopulmonary bypass. In vitro,
the binding of platelet P-selectin to leukocyte P-selectin glycoprotein lig
and-1 (PSGL1) mediates conjugate formation; however, the hemostatic implica
tions of these cell-cell interactions are unknown, The aims of this study w
ere to determine the ability of leukocytes to modulate platelet agonist-ind
uced aggregation and secretion in the blood milieu, and to investigate the
role of P-selectin and PSGL-1 in mediating these responses.
Methods: Blood was drawn from healthy volunteers for in vitro analysis of p
latelet agonist-induced aggregation secretion (adenosine triphosphate, beta
-thromboglobulin, and thromboxane), and platelet-leukocyte conjugate forma
tion. Experiments were performed on live cells in whole blood or plasma to
simulate physiologic conditions. Whole-blood impedance and optical aggregom
etry, flow cytometry, and enzyme-linked immunosorbent assays were performed
in the presence and absence of blocking antibodies to P-selectin and PSGL1
. The platelet-specific agonists, thrombin receptor activating peptide and
adenosine diphosphate, were used to elicit platelet activation responses.
Results: Inhibition of platelet-leukocyte adherence by P-selectin and PSGL1
antibodies decreased agonist-induced aggregation in whole blood. The prese
nce of leukocytes in platelet-rich plasma increased aggregation, and this i
ncrease was attenuated by P-selectin blocking antibodies. Data from flow cy
tometry confirmed that platelet-leukocyte conjugate formation contributed t
o aggregation responses. Blocking antibodies reduced platelet agonist-induc
ed thromboxane release but had no impact on adenosine triphosphate and beta
-thomboglobulin secretion.
Conclusions: Leukocytes can enhance platelet agonist-induced aggregation an
d thromboxane release in whole blood and platelet-rich plasma under shear c
onditions is vitro. Interaction of platelet P-selectin with leukocyte PSGL1
contributes substantially to these effects.