The process known as capture or tethering represents the first contact of a leukocyte with the activated endothelium. Capture occurs after margination, which allows leukocytes to move in a position close to the endothelium, away from the central blood stream. During the inflammatory response, endothelial activation is required to initiate capture.

P-selectin on endothelial cells, is the primary adhesion molecule for capture and the initiation of rolling. The main leukocyte ligand for P-selectin is PSGL-1. In addition, many in vivo studies suggest that L-selectin exhibits an important role in capture as well. Its ligand on endothelial cells is unknown. Antibodies blocking L-selectin function inhibit rolling in many models in which rolling is P-selectin dependent.

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