Submitted on June 18, 2004
Accepted on March 24, 2005
PSGL-1 Derived from Human Neutrophils is a High Efficiency Ligand for Endothelial Expressed E-selectin under Flow
Xiaoyan Zou1, Vivek R Shinde Patil1, Nilesh M Dagia1, Lee A Smith1, Maureen J Wargo1, Kimberly A Interliggi1, Christopher M Lloyd1, David F. J. Tees2, Bruce Walcheck3, Michael B Lawrance4, and Douglas J Goetz1*
1 Chemical Engineering, Ohio University, Athens, Ohio, USA
2 Physics & Astronomy, Ohio University, Athens, Ohio, USA
3 Veterinary and Biomedical Sciences, The University of Minnesota, St. Paul, Minnesota, USA
4 Biomedical Engineering, The University of Virginia, Charlottesville, Virginia, USA
* To whom correspondence should be addressed. E-mail: goetzd{at}ohio.edu.
P-selectin Glycoprotein Ligand-1 (PSGL-1) has been proposed as an important tethering ligand for E-selectin and is expressed at a modest level on human leukocytes. Sialyl Lewis x (SLex) like glycans bind to E-selectin and are expressed at a relatively high level on circulating leukocytes. It is unclear if PSGL-1 has unique biochemical attributes that contribute to its role as an E-selectin ligand. To probe this issue, we conjugated microspheres with either SLex or PSGL-1 purified from myeloid cells (neutrophils and HL60) and compared their adhesion to endothelial expressed E-selectin under defined shear conditions. We found that both SLex and PSGL-1 microspheres adhere to 4 hr. IL-1
activated human umbilical vein endothelial cells (HUVEC) predominantly through E-selectin. Analysis of the adhesion revealed that the rate of initial tethering of the PSGL-1 microspheres to E-selectin was significantly greater than the rate of initial tethering of the SLex microspheres despite the fact that the SLex microspheres tested had higher ligand densities than the PSGL-1 microspheres. We also found that pre-treatment of the PSGL-1 or SLex microspheres with HECA-452 had no significant effect on initial tethering to E-selectin. These results support the hypotheses that (i) PSGL-1 is a high efficiency tethering ligand for E-selectin, (ii) ligand biochemistry can significantly influence initial tethering to E-selectin and (iii) PSGL-1 tethering to E-selectin can occur via non-HECA-452 reactive epitopes.
