San Raffaele Scientific Institute and Università Vita-Salute San Raffaele, Milan, Italy.
Curr Opin Hematol. 2010 Jan;17(1):3-8. doi: 10.1097/MOH.0b013e3283324f97.
Platelets and neutrophils co-localize at sites of vessel injury, hemorrhage and thrombosis. Moreover, circulating platelets and leukocytes interact productively, and the formation of heterotypic aggregates is a feature of acute coronary syndromes, systemic inflammatory, neoplastic and autoimmune diseases. We have summarized the evidence suggesting a homeostatic function of the interaction, culminating in the removal of activated platelets from the bloodstream.
Anionic phospholipids, that is cell surface 'eat me' signals exposed both by activated platelets and dying cells, signals such as P-selectin (CD62P), specifically expressed by platelets, as well as of polarized clusters of neutrophils beta2 integrins play a role in the capture of platelets in vitro and in vivo.
A bona-fide synapse assembles as a consequence of the interaction between P-selectin and its counter-receptor on neutrophils, with clustering of activated beta2 integrins into membrane microdomains and reorganization of cytoskeleton components that control cell motility and phagocytosis. Actual engulfment of the tethered platelet depends on the recognition of phosphatidylserine and/or of phosphatidylserine-associated molecules. This event may have a physiologic role in the regulation of the hemostatic potential of circulating blood; conversely, a failure may contribute to persistent vascular inflammation and thrombosis.
血小板和中性粒细胞在血管损伤、出血和血栓形成部位共存。此外，循环中的血小板和白细胞之间相互作用，形成异质聚集物是急性冠状动脉综合征、全身性炎症、肿瘤和自身免疫性疾病的特征。我们总结了表明这种相互作用具有稳态功能的证据，最终将激活的血小板从血液中清除。
阴离子磷脂，即激活的血小板和死亡细胞暴露的细胞表面“吃我”信号，血小板特异性表达的 P 选择素（CD62P）以及极化的中性粒细胞β2 整合素簇在体外和体内血小板的捕获中发挥作用。
由于 P-选择素与其在中性粒细胞上的对应受体相互作用，形成了真正的突触，激活的β2 整合素簇集成为膜微区，并重新排列细胞骨架成分，控制细胞运动和吞噬作用。实际上，被束缚的血小板的吞噬取决于对磷脂酰丝氨酸和/或磷脂酰丝氨酸相关分子的识别。这一事件可能在调节循环血液的止血潜能方面具有生理作用；相反，失败可能导致持续的血管炎症和血栓形成。
