title: Direct quantification of the modulation of interaction between cell- or surface-bound LFA-1 and ICAM-1.
abstract: The functional activity of leukocyte integrins is highly regulated by several mechanisms related to intrinsic molecular properties and receptor interaction with the cell membrane. Here, we present a microkinetic study of the lymphocyte function-associated antigen-1-mediated interaction between flowing Jurkat cells and surface- or cell-bound intercellular adhesion molecule-1 (ICAM-1). We conclude that adhesion is initiated by the formation of a single bond with approximately 0.3 s(-1) dissociation rate, and attachment is subsequently strengthened by the formation of additional bonds during the next 10 s; exposing cells to Mg2+ or Mn2+ resulted in up to a 16-fold increase of the binding frequency, in line with reported measurements performed on isolated molecules with surface plasmon resonance methodology; cell-bound ICAM-1 molecules were more efficient in mediating adhesion than Fc-ICAM-1, properly oriented and bound by surface-adsorbed protein A; and quantitative analysis of binding frequency suggested that adhesion efficiency was ten- to 100-fold lower than the maximum value allowed by previously determined association rates of soluble molecules. It is concluded that the presented methodology provides a simple and unique way of dissecting the initial step of cell adhesion and discriminating between affinity and avidity modulation of adhesion receptors.
authors.affiliation: Laboratory of Immunology, INSERM U600, CNRS FRE 2059, Univ. Mediterranée, Hôpital de Ste-Marguerite, 270 Bd de Ste-Marguerite, 13009 France.
authors.forename: Joana
authors.initials: J
authors.lastname: Vitte
authors.forename: Anne
authors.initials: A
authors.lastname: Pierres
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Benoliel
authors.forename: Pierre
authors.initials: P
authors.lastname: Bongrand
mesh_terms: D000906:Antibodies / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites / Q000187:drug effects / Q000276:immunology; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology; D002462:Cell Membrane / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism*; D019169:Jurkat Cells; D007962:Leukocytes / Q000276:immunology / Q000502:physiology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects / Q000276:immunology; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
chemical_list: D000906:Antibodies; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1; D008345:Manganese; D008274:Magnesium