P-selectin glycoprotein ligand-1 mediates rolling of human neutrophils on P-selectin.

Abstract

Abstract. Neutrophils roll on P-selectin expressed by activated platelets or endothelial cells under the shear stresses in the microcirculation. P-selectin glycoprotein ligand-1 (PSGL-1) is a high affinity ligand for P-selectin on myeloid cells. However, it has not been demonstrated that PSGL-1 contributes to the rolling of neutrophils on P-selectin. We developed two IgG mAbs, PL1 and PL2, that appear to recognize proteindependent epitopes on human PSGL-1. The mAbs bound to PSGL-1 on all leukocytes as well as on heterologous cells transfected with PSGL-1 cDNA. PL1, but not PL2, blocked binding of '25I-PSGL-1 to immobilized P-selectin, binding of fluid-phase P-selectin to myeloid and lymphoid leukocytes, adhesion of neutrophils to immobilized P-selectin under static conditions, and rolling of neutrophils on P-selectinexpressing CHO cells under a range of shear stresses. PSGL-1 was localized to microvilli on neutrophils, a topography that may facilitate its adhesive function. These data indicate that (a) PSGL-1 accounts for the high affinity binding sites for P-selectin on leukocytes, and (b) PSGL-1 must interact with P-selectin in order for neutrophils to roll on P-selectin at physiological shear stresses. TH~ selectins are a family of three Ca2+-dependent membrane-bound lectins that initiate the rolling adhesion of leukocytes to platelets or endothelial cells under the shear forces found in the venular circulation (6,25,33). L-selectin, expressed on leukocytes, binds to constitutive or inducible ligands on endothelial cells. E-selectin, expressed by cytokine-activated endothelial cells, and P-selectin, expressed by thrombin-activated platelets and endothelial cells, bind to ligands on myeloid cells and subsets of lymphocytes. Although the selectins interact weakly with small sialylated, fucosylated oligosaccharides such as sialyl Lewis x (Galfll-4[Fuccd-3lGlcNAc) (Le~) ~ (17, 50), they bind with higher affinity to glycans displayed on a limited number of glycoproteins (3,5,20,26,28,29,39,52) or proteoglycans (41). A major unresolved issue is whether selectins must bind to these higher affinity, but less abundant, ligands in order for leukocytes to roll on the vessel wall un-

SELPLG Gene Polymorphisms in Relation to Plasma SELPLG Levels and Coronary Artery Disease

“…In particular, the haplotype analysis revealed that the I62 allele was associated with increased SELPLG levels independently of other polymorphisms. The non-synonymous M62I polymorphism is located at the border of the binding region of SELPLG to P-selectin (Li et al 1996;Lim et al 1998;Moore et al 1995), and it might be hypothesized that the I62 allele modifies the affinity of SELPLG to P-selectin, and the subsequent release of SELPLG in the circulation. On the other hand, the M62I polymorphism is also located within the epitope domain of one of the monoclonal antibodies (PL1) used for measuring plasma SELPLG levels (Li et al 1996), and it cannot be ruled out that the observed effect on SELPLG levels is artefactual, due to a higher affinity of the PL1 antibody to the protein encoded by the I62 allele.…”

Extensive platelet activation in preeclampsia compared with normal pregnancy: Enhanced expression of cell adhesion molecules

“…On the monocyte the ligand involved in the binding to P-selectin has been identified. 24 The platelet-monocyte binding causes the increased expression of tissue factor, a major initiator of the coagulation system, on the monocyte. Thus increased P-selectin expression on the platelet facilitates plateletleukocyte and possibly platelet-endothelial cell interactions.…”

Variation in the upstream region of P-Selectin (SELP) is a risk factor for SLE

“…[11][12][13][14] The protein functions as an adhesion molecule for a variety of leukocytes, including neutrophils, monocytes, T cells, eosinophils, basophils, platelets and some malignant cells, 15 thereby bringing to sites of inflammation and into contact with a range of cytokines and chemokines expressed by endothelial cells. There are two receptors for P-Selectin, the major leukocyte receptor, P-selectin glycoprotein ligand 1 (PSGL1), which is the high affinity receptor on both myeloid cells and stimulated T lymphocytes, 16,17 and CD24, which is expressed on a number of cells, including B-lineage cells and T lymphocytes. 18 Furthermore, the 57 V allele of CD24 has also been recently described as a susceptibility allele for lupus in a Spanish population 18 and for both multiple sclerosis 19 and rheumatoid arthritis.…”