Abstract
Lymphocyte homing is initiated by the binding of L-selectin on lymphocytes to its ligands on high endothelial venules (HEV). Sialyl 6-sulfo Lewis X is a major capping group of L-selectin ligands. N-Acetylglucosamine (GlcNAc) 6-sulfation is essential for the ligand activity, and is catalyzed by GlcNAc 6-O-sulfotransferases (GlcNAc6STs) of which GlcNAc6ST-1 and GlcNAc6ST-2 are expressed in HEV. Here, we report that mice deficient in GlcNAc6ST-1 were impaired in the elaboration of sialyl 6-sulfo Lewis X in HEV and that an epitope of L-selectin ligands recognized by the MECA-79 anti-body was greatly reduced or abolished in the abluminal aspect of HEV. Lymphocyte homing to peripheral lymph nodes, mesenteric lymph nodes, and Peyer's patches was significantly reduced in GlcNAc6ST-1 null mice. These results demonstrate that GlcNAc6ST-1 is involved in lymphocyte homing in vivo, and indicate that GlcNAc6ST-1 and -2 play complementary roles. The importance of GlcNAc6ST-1 is particularly high-lighted by its involvement in lymphocyte homing to Peyer's patches where GlcNAc6ST-2 expression is undetectable.