HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY Severe impairment of leukocyte rolling in venules of core 2 glucosaminyltransferase–deficient mice

Leukocyte capture and rolling are mediated by selectins expressed on leukocytes (L-selectin) and the vascular endothelium (Pand E-selectin). To investigate the role of core 2 b1-6-N-glucosaminyltransferase (C2GlcNAcT-I) for synthesis of functional selectin ligands in vivo, leukocyte rolling flux and velocity were studied in venules of untreated and tumor necrosis factor-a (TNFa)–pretreated autoperfused cremaster muscles of C2GlcNAcT-I–deficient (core 22/2) and littermate control mice. In untreated core 22/2 mice, leukocyte rolling was dramatically reduced with markedly increased rolling velocities (81 6 4 mm/s vs 44 6 3 mm/s). The reduced rolling in core 22/2 mice was due mainly to severely impaired binding of P-selectin to P-selectin glycoprotein ligand-1 (PSGL-1). Some rolling remained after blocking PSGL-1 in controls but not in core 22/2 mice. In TNFapretreated mice, rolling was markedly reduced in core 22/2 mice owing to impaired P-selectin– and E-selectin–mediated rolling. Rolling velocities in core 22/2 mice treated with an E-selectin–blocking monoclonal antibody (59 6 4 mm/s) were significantly higher than in controls (14 6 1 mm/s), which provides further evidence for the severe impairment in P-selectin– mediated rolling. In conclusion, P-selectin ligands including PSGL-1 are largely C2GlcNAcT-I dependent. In addition, Eselectin–mediated rolling in vivo is partially dependent on the targeted C2GlcNAcT-I. (Blood. 2001;97:3812-3819)