A CHEMOKINE EXPRESSED IN LYMPHOID HIGH ENDOTHELIAL VENULES PROMOTES THE ADHESION AND CHEMOTAXIS OF NAIVE T-LYMPHOCYTES

Preferential homing of naive lymphocytes to secondary lymphoid organs is thought to involve the action of chemokines, yet no chemokine has b een shown to have either the expression pattern or the activities requ ired to mediate this process, Here we show that a chemokine represente d in the EST database, secondary lymphoid-tissue chemokine (SLC), is e xpressed in the high endothelial venules of lymph nodes and Peyer's pa tches, in the T cell areas of spleen, lymph nodes, and Peyer's patches , and in the lymphatic endothelium of multiple organs. SLC is a highly efficacious chemoattractant for lymphocytes with preferential activit y toward naive T cells, Moreover, SLC induces firm adhesion of naive T lymphocytes via beta 2 integrin binding to the counter receptor, inte rcellular adhesion molecule-1, a necessary step for lymphocyte recruit ment, SLC is the first chemokine demonstrated to have the characterist ics required to mediate homing of lymphocytes to secondary lymphoid or gans, In addition, the expression of SLC in lymphatic endothelium sugg ests that the migration of lymphocytes from tissues into efferent lymp hatics may be an active process mediated by this molecule.