title: Heterotropic modulation of selectin affinity by allosteric antibodies affects leukocyte rolling.
abstract: Selectins are a family of adhesion receptors designed for efficient leukocyte tethering to the endothelium under shear. As a key property to resist premature bond disruption, selectin adhesiveness is enhanced by tensile forces that promote the conversion of a bent into an extended conformation of the N-terminal lectin and epidermal growth factor-like domains. Conformation-specific Abs have been invaluable in deciphering the activation mechanism of integrins, but similar reagents are not available for selectins. In this study, we show that the anti-human L-selectin mAbs DREG-55 and LAM1-5 but not DREG-56, DREG-200, or LAM1-1 heterotropically modulate adhesion presumably by stabilizing the extended receptor conformation. Force-free affinity assays, flow chamber, and microkinetic studies reveal a ligand-specific modulation of L-selectin affinity by DREG-55 mAb, resulting in a dramatic decrease of rolling velocity under flow. Furthermore, secondary tethering of polymorphonuclear cells was blocked by DREG-200 but significantly boosted by DREG-55 mAb. The results emphasize the need for a new classification for selectin Abs and introduce the new concept of heterotropic modulation of receptor function.
authors.affiliation: Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité-University of Medicine Berlin, 10117 Berlin, Germany;
authors.forename: Sebastian B
authors.initials: SB
authors.lastname: Riese
authors.forename: Christian
authors.initials: C
authors.lastname: Kuehne
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Tedder
authors.forename: Rupert
authors.initials: R
authors.lastname: Hallmann
authors.forename: Erhard
authors.initials: E
authors.lastname: Hohenester
authors.forename: Konrad
authors.initials: K
authors.lastname: Buscher
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology*; D002448:Cell Adhesion / Q000276:immunology; D002460:Cell Line; D006801:Humans; D019169:Jurkat Cells; D036904:Leukocyte Rolling / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D019087:Selectins / Q000276:immunology / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D019087:Selectins