Selectin Ligands on T Cells

L-selectin was the first member of the selectin family identified by its function as lymphocyte homing receptor and key mediator of T cell recirculation through lymph nodes (Gallatin et al. 1983). E- and P-selectin, detected later, were not only found differentially distributed, i.e., restricted to the endothelial cell side, but also associated with inflammation rather than with homeostatic lymphocyte recirculation (Pober and Cotran 1990). A large body of data shows that both E- and P-selectin become upregulated in vitro and in vivo upon action of inflammatory mediators such as tumor necrosis factor (TNF) or others on endothelium of various tissues (Kansas 1996; McEver 1997; Vestweber 1997; Patel et al. 2002). Recruitment of myeloid cells, which express constitutively ligands for endothelial cells, is a major consequence, but early studies also reported binding of memory T cells to endothelium expressing E- or P-selectin (Shimizu et al. 1991).