title: Polarity of T cell shape, motility, and sensitivity to antigen.
abstract: T cell activation requires contact with APCs. We used optical techniques to demonstrate T cell polarity on the basis of shape, motility, and localized sensitivity to antigen. An intracellular Ca2+ clamp showed that T cell shape and motility are extremely sensitive to changes in [Ca2+]i (Kd = 200 nM), with immobilization and rounding occurring via a calcineurin-independent pathway. Ca2+ dependent immobilization prolonged T cell contact with the antigen-presenting B cell; buffering the [Ca2+]i signal prevented the formation of stable cell pairs. Optical tweezers revealed spatial T cell sensitivity to antigen by controlling placement on the T cell surface of either B cells or alpha-CD3 MAb-coated beads. T cells were 4-fold more sensitive to contact made at the leading edge of the T cell compared with the tail. We conclude that motile T cells are polarized antigen sensors that respond physically to [Ca2+]i signals to stabilize their interaction with APCs.
authors.affiliation: Department of Physiology and Biophysics, University of California, Irvine 92717, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Negulescu
authors.forename: T B
authors.initials: TB
authors.lastname: Krasieva
authors.forename: A
authors.initials: A
authors.lastname: Khan
authors.forename: H H
authors.initials: HH
authors.lastname: Kerschbaum
authors.forename: M D
authors.initials: MD
authors.lastname: Cahalan
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000502:physiology; D001402:B-Lymphocytes / Q000502:physiology; D002118:Calcium / Q000502:physiology; D002450:Cell Communication / Q000276:immunology; D002460:Cell Line; D002465:Cell Movement / Q000276:immunology*; D016764:Cell Polarity / Q000276:immunology*; D005898:Glass; D006801:Humans; D051379:Mice; D008846:Micromanipulation; D055095:Optics and Photonics; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology; D013696:Temperature
chemical_list: D002118:Calcium