Platelet-mediated enhancement of leukocyte adhesion.

Recruitment of inflammatory cells in the perivascular tissue is a necessity for many physiological processes. While the inflammatory influx of cells to combat infection near the entrance site of infective agents is protective, it also drives the development of diseases, such as atherosclerosis. We know from the multistep model that cellular recruitment consists of overlapping sequences initiated by capturing and rolling of the cell, followed by adhesion, which is of paramount importance and indispensable for the subsequent transendothelial migration. The spectrum of molecules and cells involved in these processes is vast. Platelets have evolved in several ways as amplifiers of leukocyte adhesion, since beyond their central role in primary hemostasis, their repertoire of adhesion molecules and soluble mediators renders them important interplayers between endothelial cells and blood-borne immune cells.