title: Immune synapse formation determines interaction forces between T cells and antigen-presenting cells measured by atomic force microscopy.
abstract: During adaptive immune responses, T lymphocytes recognize antigenic peptides presented by MHC molecules on antigen-presenting cells (APCs). This recognition results in the formation of a so-called immune synapse (IS) at the T-cell/APC interface, which is crucial for T-cell activation. The molecular composition of the IS has been extensively studied, but little is known about the biophysics and interaction forces between T cells and APCs. Here, we report the measurement of interaction forces between T cells and APCs employing atomic force microscopy (AFM). For these investigations, specific T cells were selected that recognize an antigenic peptide presented by MHC-class II molecules on APCs. Dynamic analysis of T-cell/APC interaction by AFM revealed that in the presence of antigen interaction forces increased from 1 to 2 nN at early time-points to a maximum of approximately 14 nN after 30 min and decreased again after 60 min. These data correlate with the kinetics of synapse formation that also reached a maximum after 30 min, as determined by high-throughput multispectral imaging flow cytometry. Because the integrin lymphocyte function antigen-1 (LFA-1) and its counterpart intercellular adhesion molecule-1 (ICAM-1) are prominent members of a mature IS, the effect of a small molecular inhibitor for LFA-1, BIRT377, was investigated. BIRT377 almost completely abolish the interaction forces, emphasizing the importance of LFA-1/ICAM-1-interactions for firm T-cell/APC adhesion. In conclusion, using biophysical measurements, this study provides precise values for the interaction forces between T cells and APCs and demonstrates that these forces develop over time and are highest when synapse formation is maximal.
authors.affiliation: Department of New Materials and Biosystems, Max-Planck-Institute for Metals Research, Stuttgart, Germany.
authors.forename: Babak H
authors.initials: BH
authors.lastname: Hosseini
authors.forename: Ilia
authors.initials: I
authors.lastname: Louban
authors.forename: Dominik
authors.initials: D
authors.lastname: Djandji
authors.forename: Guido H
authors.initials: GH
authors.lastname: Wabnitz
authors.forename: Janosch
authors.initials: J
authors.lastname: Deeg
authors.forename: Nadja
authors.initials: N
authors.lastname: Bulbuc
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Samstag
authors.forename: Matthias
authors.initials: M
authors.lastname: Gunzer
authors.forename: Joachim P
authors.initials: JP
authors.lastname: Spatz
authors.forename: Günter J
authors.initials: GJ
authors.lastname: Hämmerling
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology* / Q000502:physiology; D002448:Cell Adhesion / Q000502:physiology; D002450:Cell Communication; D002460:Cell Line; D006825:Hybridomas / Q000276:immunology / Q000502:physiology; D048289:Imidazolidines / Q000494:pharmacology; D054992:Immunological Synapses / Q000502:physiology*; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D051379:Mice; D018625:Microscopy, Atomic Force; D009113:Muramidase / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology
chemical_list: C400461:BIRT 377; D048289:Imidazolidines; D016169:Lymphocyte Function-Associated Antigen-1; D010446:Peptide Fragments; D018799:Intercellular Adhesion Molecule-1; C421864:hen egg lysozyme; D009113:Muramidase