title: Single-particle tracking of immunoglobulin E receptors (FcεRI) in micron-sized clusters and receptor patches.
abstract: When mast cells contact a monovalent antigen-bearing fluid lipid bilayer, IgE-loaded FcεRI receptors aggregate at contact points and trigger degranulation and the release of immune activators. We used two-color total internal reflection fluorescence microscopy and single-particle tracking to show that most fluorescently labeled receptor complexes diffuse freely within these micron-size clusters, with a diffusion coefficient comparable to free receptors in resting cells. At later times, when the small clusters coalesce to form larger patches, receptors diffuse even more rapidly. In all cases, Monte Carlo diffusion simulations ensured that the tracking results were free of bias, and distinguished biological from statistical variation. These results show the diversity in receptor mobility in mast cells, demonstrating at least three distinct states of receptor diffusivity.
authors.affiliation: Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Spendier
authors.forename: Keith A
authors.initials: KA
authors.lastname: Lidke
authors.forename: Diane S
authors.initials: DS
authors.lastname: Lidke
authors.forename: James L
authors.initials: JL
authors.lastname: Thomas
mesh_terms: D000818:Animals; D015550:Cell Degranulation; D002460:Cell Line; D004058:Diffusion; D005456:Fluorescent Dyes; D007073:Immunoglobulin E / Q000378:metabolism; D008051:Lipid Bilayers; D008407:Mast Cells / Q000276:immunology; D008856:Microscopy, Fluorescence; D009010:Monte Carlo Method; D051381:Rats; D011940:Receptor Aggregation; D017455:Receptors, IgE / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D017455:Receptors, IgE; D007073:Immunoglobulin E