Fa. Symon et al., FUNCTIONAL AND STRUCTURAL CHARACTERIZATION OF THE EOSINOPHIL P-SELECTIN LIGAND, The Journal of immunology, 157(4), 1996, pp. 1711-1719
Our recent studies have indicated an important role for P-selectin in
eosinophil adhesion, We have therefore compared eosinophil and neutrop
hil binding with nasal polyp endothelium as well as purified P-selecti
n. We have also compared the structure and expression of the eosinophi
l and neutrophil P-selectin ligands. Using the frozen section assay, e
osinophils bound to 2-fold more blood vessels within the nasal polyp t
issue than neutrophils. Up to 10-fold more eosinophils than neutrophil
s bound per unit length of endothelium, Neutrophil and eosinophil bind
ing was inhibited by a mAb against P-selectin and a P-selectin chimera
which binds to the P-selectin ligand. Eosinophils bound with approxim
ately 2-fold greater avidity to purified P-selectin under now conditio
ns, Using SDS-PAGE we characterized the eosinophil P-selectin ligand a
s a sialylated, homodimeric glycoprotein consistent with the known str
ucture of PSGL-1. However, expression of PSGL-1 by eosinophils was sig
nificantly greater than on neutrophils. The eosinophil ligand had a ca
lculated molecular mass by SDS-PACE of approximately 10 kDa greater th
an the neutrophil ligand, which was not due to differences in N-glycos
ylation. Eosinophils expressed the 15-decapeptide repeat form of PSGL-
1 compared with neutrophils that have the 16-decapeptide repeat form,
The increased binding of eosinophils, compared with neutrophils, to P-
selectin in both an ex-vivo and in vitro assay suggests that P-selecti
n may have a role directing the specific migration of eosinophils in d
iseases such as asthma. The increased avidity may be due to increased
expression of PSGL-1 by eosinophils, differences in the peptide backbo
ne, or post-translational modifications.