title: Evidence for a third component in neutrophil aggregation: potential roles of O-linked glycoproteins as L-selectin counter-structures.
abstract: The homotypic aggregation of neutrophils requires the participation of L-selectin and the beta 2-integrins, but it has not been clear whether the two receptors recognize one another as counter-structures or whether other adhesion molecules are involved. We have examined aggregation of live neutrophils with target populations, manipulated to alter expression of adhesive epitopes, using flow cytometry. A target population depleted of both L-selectin and activatable beta 2-integrin displayed an ability to aggregate with live neutrophils, suggesting that these two molecules are not counter-structures. We also found that an O-sialoglycoprotease (GCP) from Pasteurella haemolytica is capable of inhibiting homotypic aggregation. Neutrophils treated with GCP lose O-glycosylated proteins but retain L-selectin and activatable beta 2-integrin. One or more of the GCP substrates appears to function in L-selectin-dependent binding but not in beta 2-integrin-dependent binding. Together the data suggest a mechanism of aggregation that is analogous to leukocyte-endothelial cell adhesion in which a low-affinity carbohydrate-dependent interaction precedes a high-affinity integrin-dependent adhesion.
authors.affiliation: Department of Pathology, University of New Mexico, School of Medicine, Albuquerque 87131, USA.
authors.forename: T A
authors.initials: TA
authors.lastname: Bennett
authors.forename: C M
authors.initials: CM
authors.lastname: Schammel
authors.forename: E B
authors.initials: EB
authors.lastname: Lynam
authors.forename: D A
authors.initials: DA
authors.lastname: Guyer
authors.forename: A
authors.initials: A
authors.lastname: Mellors
authors.forename: B
authors.initials: B
authors.lastname: Edwards
authors.forename: S
authors.initials: S
authors.lastname: Rogelj
authors.forename: L A
authors.initials: LA
authors.lastname: Sklar
mesh_terms: D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002449:Cell Aggregation; D002634:Chemotaxis, Leukocyte; D006801:Humans; D066298:In Vitro Techniques; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D019041:L-Selectin / Q000378:metabolism*; D008024:Ligands; D009504:Neutrophils / Q000166:cytology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D012795:Sialoglycoproteins / Q000378:metabolism*; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D015815:Cell Adhesion Molecules; D007461:Iodoacetates; D008024:Ligands; D011956:Receptors, Cell Surface; D012795:Sialoglycoproteins; D013439:Sulfhydryl Reagents; D019041:L-Selectin; D019807:Iodoacetic Acid