Schematic summary of the endothelial CD47 association with SIRPγ in T cells. SIRPγ is selectively expressed and localized on the surface of CD3⁺ T cells and binds to endothelial CD47 in trans. Because SIRPγ contains a short cytoplasmic tail and is believed not to signal to the T cells, we propose a model in which CD47 engagement by SIRPγ promotes CD47-induced signaling pathways in endothelial cells (unidirectional). These signals could facilitate TEM by G_i-coupled signaling and/or through association with integrins in cis that may occur in endothelial cells. For example, CD47 ligation by SIRPγ could induce actin cytoskeleton remodeling and disassembly of the adherent junctions in endothelial cells, processes that are required for a successful T-cell transendothelial migration.^36,37  Disruption of the CD47-SIRYγ complex by CD47- and SIRPγ-specific blocking monoclonal antibodies strongly reduced T-cell transmigration under flow conditions in vitro.