title: Distinct divalent cation requirements for integrin-mediated CD4+ T lymphocyte adhesion to ICAM-1, fibronectin, VCAM-1, and invasin.
abstract: Integrins are a large family of cell surface receptors that mediate the adhesion of cells to other cells and to components of the extracellular matrix. Various divalent cations, particularly Ca2+ and Mn2+, have been shown to modulate the functional activity of many different integrins expressed on a wide variety of cell types. In this study, we have characterized the divalent cation requirements for the adhesion of human peripheral CD4+ T cells to four distinct integrin ligands: the alpha 4 beta 1 and alpha 5 beta 1 ligand fibronectin, the alpha 4 beta 1 ligand VCAM-1, the LFA-1 ligand ICAM-1, and the alpha 4 beta 1 bacterial ligand invasin. We find that there are distinct divalent cation requirements for T cell adhesion to each of these ligands: 1) Mg2+/EGTA treatment selectively up-regulates T cell adhesion to ICAM-1; 2) Mn2+ coordinately up-regulates adhesion to ICAM-1, fibronectin, and VCAM-1, with a peak response at 100 microM Mn2+; 3) Ca2+ can selectively support adhesion to VCAM-1 induced by activation and inhibit Mn(2+)-dependent adhesion to ICAM-1; and 4) binding to invasin is maximal in the presence of Ca2+, Mg2+, or Mn2+. Furthermore, divalent cation modifications do not fully up-regulate T cell adhesion to fibronectin, VCAM-1, and ICAM-1, because additional cell activation with phorbol ester treatment can further enhance adhesion in the presence of Mn2+. These results suggest that modification of divalent cations may provide a mechanism by which an individual integrin receptor/ligand interaction can be specifically and selectively regulated.
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109.
authors.forename: Y
authors.initials: Y
authors.lastname: Shimizu
authors.forename: J L
authors.initials: JL
authors.lastname: Mobley
mesh_terms: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000502:physiology*; D004533:Egtazic Acid / Q000494:pharmacology; D005353:Fibronectins / Q000502:physiology*; D006801:Humans; D016023:Integrins / Q000502:physiology*; D018799:Intercellular Adhesion Molecule-1; D008345:Manganese / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015854:Up-Regulation; D019010:Vascular Cell Adhesion Molecule-1
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D015815:Cell Adhesion Molecules; D005353:Fibronectins; D016023:Integrins; D019010:Vascular Cell Adhesion Molecule-1; C053476:invasin, Yersinia; D018799:Intercellular Adhesion Molecule-1; D008345:Manganese; D004533:Egtazic Acid; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium