title: The immune synapse clears and excludes molecules above a size threshold.
abstract: Natural killer cells assess target cell health via interactions at the immune synapse (IS) that facilitates signal integration and directed secretion. Here we test whether the IS also functions as a gasket. Quantitative fluorescence microscopy of nanometer-scale dextrans within synapses formed by various effector-target cell conjugates reveal that molecules are excluded in a size-dependent manner at activating synapses. Dextran sized ≤4 nm move in and out of the IS, but access is significantly reduced (by >50%) for dextran sized 10-13 nm, and dextran ≥32 nm is almost entirely excluded. Depolymerization of F-actin abrogated exclusion. Unexpectedly, larger-sized dextrans are cleared as the IS assembles in a zipper-like manner. Monoclonal antibodies are also excluded from the IS but smaller single-domain antibodies are able to penetrate. Therefore, the IS can clear and exclude molecules above a size threshold, and drugs designed to target synaptic cytokines or cytotoxic proteins must fit these dimensions.
authors.affiliation: 1] Manchester Collaborative Centre for Inflammation Research, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK [2] Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK.
authors.forename: Adam N R
authors.initials: AN
authors.lastname: Cartwright
authors.affiliation: GlaxoSmithKline, Gunnels Wood Road, Stevenage, Herts SG1 2NY, UK.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Griggs
authors.affiliation: Manchester Collaborative Centre for Inflammation Research, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Davis
mesh_terms: D000199:Actins / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000378:metabolism; D003911:Dextrans / Q000378:metabolism; D006801:Humans; D054992:Immunological Synapses / Q000276:immunology / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D015398:Signal Transduction; D061905:Single-Domain Antibodies / Q000378:metabolism
chemical_list: D000199:Actins; D000911:Antibodies, Monoclonal; D003911:Dextrans; D061905:Single-Domain Antibodies