title: Distinct phenotype of E-selectin-deficient mice. E-selectin is required for slow leukocyte rolling in vivo.
abstract: Leukocyte capture and rolling are mediated by calcium-dependent lectins expressed on most leukocytes (L-selectin) and the vascular endothelium (P- and E-selectin). To study the role of the selectins during inflammation, we have investigated leukocyte rolling in venules of tumor necrosis factor-alpha (TNF-alpha)-treated mouse cremaster muscles in wild-type mice and gene-targeted mice with homozygous deficiency for L-, P-, or E-selectin (L-/-, P-/-, or E-/-, respectively). TNF-alpha treatment induces expression of E-selectin and increases expression of P-selectin on endothelial cells. Consistent with previous reports of redundant P- and E-selectin function, a combination of monoclonal antibodies (mAbs) against P- and E-selectin (RB40.34 and 9A9, respectively) was necessary to block rolling in wild-type mice. The rolling leukocyte flux fraction (percent rolling cells) in L-/- mice was similar to that in wild-type mice, but rolling in these mice was blocked by a P-selectin mAb. The velocity of rolling leukocytes in TNF-alpha-treated wild-type, P-/-, or L-/- mice was 5 to 10 times slower (3 to 7 microns/s) than during trauma-induced rolling (20 to 50 microns/s). In contrast, leukocytes in venules of TNF-alpha-treated E-/- mice rolled significantly faster (12 to 20 microns/s): the rolling leukocyte flux fraction was more than doubled compared with wild-type, L-/-, or P-/- mice; and the number of adherent leukocytes was reduced. Addition of an E-selectin mAb, but not a P-selectin mAb, increased rolling flux fraction and rolling velocity in wild-type mice. Histological analysis revealed that 90% to 95% of all leukocytes interacting (rolling and adherent) with the venular endothelium in TNF-alpha-treated wild-type, L-/-, P-/-, and E-/- mice were granulocytes. These results identify a previously unrecognized phenotype of E-/- mice by establishing that at the site densities prevailing in vivo, E-selectin in responsible for slow (approximately 5 microns/s) granulocyte rolling. E-selectin-dependent slow rolling drastically increases the transit time of leukocytes rolling through an inflamed tissue and thus aids in targeting leukocytes activated by chemoattractants to the inflammatory microenvironment.
authors.affiliation: Department of Biomedical Engineering, University of Virginia School of Medicine, Charlottesville 22908, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Kunkel
authors.forename: K
authors.initials: K
authors.lastname: Ley
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D019040:E-Selectin / Q000235:genetics / Q000502:physiology*; D007962:Leukocytes / Q000166:cytology / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000098:blood supply*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014699:Venules / Q000502:physiology*
chemical_list: D000911:Antibodies, Monoclonal; D019040:E-Selectin; D014409:Tumor Necrosis Factor-alpha