Platelet adhesion to PMN is also dependent on von Willebrand factor

MAUGERI N; SCHATTNER M; LAZZARI MA

Paris, Francia

Congreso; XVIIIth Congress. International Society for Thrombosis and Haemostasis; 2001

International Society for Thrombosis and Haemostasis

PLATELET ADHESION TO PMN IS ALSO DEPENDENT ON VON WILLEBRAND FACTOR. Norma Maugeri, Mirta Schattner,  Maria A Lazzari. CONICET. Hematological Research Institute. National Academy of Medicine. Buenos Aires, Argentina.   Von Willebrand factor (vWF) and adhesive interactions between blood cells play a important role in hemostasis. PMN express different receptors (CD11b/CD18, CD11c/CD18, PSGL-1) that are involved to the platelet adhesion. We have previously reported the presence of vWF on PMN surface. In the present study, we have analyzed the adhesion of  platelets and PMN mediated by vWF under flowing conditions. Washed  human platelets and PMN were exposed to a shear rate of 250/s at 37°C during 3 min. Under these conditions, the formation of mixed cell aggregates (MCA) was confirmed by flow cytometry. For blocking assays platelets or PMN were incubated for 10 min with saturating concentrations of the following antibodies: SZ1= anti glycoprotein (GP) Ib, AK4= anti P-selectin, DREG56= anti L- selectin, ICRF4= anti alpha chain of CD11b/CD18 and 7E4= anti alpha chain of CD18 or with aurin tricarboxylic acid (ATA), which blocks the GPIb recognition site on the vWF. The MCA formation (23±7%) was efficienty blocked by SZ1 (7±2%,  n=8, p<0.05) and by 10µM of ATA (5±1%, n=5, p<0.05). No significant differences were observed with ICFR44 (19±4%, n=3), 7E4 (22±3%, n=3), DREG56 (19±5, n=3) or AK4 (14±3, n=3). All these results suggest that platelet GPIb binds to the vWF present on the PMN surface.