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 (P- and E-selectin), To investigate the role of core 2 beta1-B-N-glucosaminyl- transferase (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-alpha (TNF alpha)-pretreated autoperfused cremaster muscles of C2GlcNAcT-I-deficient (core 2(-/-)) and littermate control mice. In untreated core 2(-/-) mice, leukocyte rolling was dramatically reduced with markedly increased rolling velocities (81 +/- 4 4 mum/s vs 44 +/- 3 mum/s), The reduced rolling in core 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 2(-/-) mice. In TNF alpha -pretreated mice, rolling was markedly reduced in core 2-/- mice owing to impaired P-selectin- and E-selectin-mediated rolling. Rolling velocities in core 2(-/-) mice treated with an E-selectin-blocking monoclonal antibody (59 +/- 4 mum/s) were significantly higher than in controls (14 +/- mum/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, E-selectin-mediated rolling in vivo is partially dependent on the targeted C2GlcNAcT-I.