BACKGROUND: Blood-borne tissue factor (TF) plays a crucial role in thrombogenesis. AIM: To study whether polymorphonuclear leukocytes (PMN) are a source of TF. METHODS AND RESULTS: Human PMN were carefully separated from other blood cells and stimulated for 3 min with purified P-selectin or the chemotactic peptide formyl-MetLeuPhe (fMLP): they expressed both TF procoagulant activity, as identified by specific TF MoAb and inactivated factor VIIa blockade; and TF:Ag (four to six times), as shown by flow-cytometry and immunocytochemistry. About 40% of permeabilized PMN, both resting and stimulated, contained TF:Ag, indicating that stimulation only modifies the location of TF:Ag within PMN. By real time-polymerase chain reaction (RT-PCR), a very low amount of TF mRNA was detectable in resting PMN, but a 3- to 5-fold increase was observed after 1-h stimulation with P-selectin or fMLP, respectively. CONCLUSIONS: These findings suggest that TF is not constitutively expressed in peripheral PMN, but can be up-regulated and produced upon stimulation and specific gene transcription, as for instance during contact with activated platelets or endothelium. The stored TF is rapidly expressed in vitro as a functional molecule on the surface of activated PMN. The availability of PMN TF supports the relevance of inflammatory cells and their interaction with platelets for fibrin deposition and thrombus formation.
BACKGROUND: Blood-borne tissue factor (TF) plays a crucial role in thrombogenesis. AIM: To study whether polymorphonuclear leukocytes (PMN) are a source of TF. METHODS AND RESULTS:Human PMN were carefully separated from other blood cells and stimulated for 3 min with purified P-selectin or the chemotactic peptide formyl-MetLeuPhe (fMLP): they expressed both TF procoagulant activity, as identified by specific TF MoAb and inactivated factor VIIa blockade; and TF:Ag (four to six times), as shown by flow-cytometry and immunocytochemistry. About 40% of permeabilized PMN, both resting and stimulated, contained TF:Ag, indicating that stimulation only modifies the location of TF:Ag within PMN. By real time-polymerase chain reaction (RT-PCR), a very low amount of TF mRNA was detectable in resting PMN, but a 3- to 5-fold increase was observed after 1-h stimulation with P-selectin or fMLP, respectively. CONCLUSIONS: These findings suggest that TF is not constitutively expressed in peripheral PMN, but can be up-regulated and produced upon stimulation and specific gene transcription, as for instance during contact with activated platelets or endothelium. The stored TF is rapidly expressed in vitro as a functional molecule on the surface of activated PMN. The availability of PMN TF supports the relevance of inflammatory cells and their interaction with platelets for fibrin deposition and thrombus formation.
Authors: Andrea Morotti; Chia-Ling Phuah; Christopher D Anderson; Michael J Jessel; Kristin Schwab; Alison M Ayres; Alessandro Pezzini; Alessandro Padovani; M Edip Gurol; Anand Viswanathan; Steven M Greenberg; Joshua N Goldstein; Jonathan Rosand Journal: Stroke Date: 2016-04-21 Impact factor: 7.914