Cytotoxic T lymphocytes form an antigen-independent ring junction
Kristina Somersalo, … , Yuri Sykulev, Michael L. Dustin
Kristina Somersalo, … , Yuri Sykulev, Michael L. Dustin
Published January 1, 2004
Citation Information: J Clin Invest. 2004;113(1):49-57. https://doi.org/10.1172/JCI19337.
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Article Immunology

Cytotoxic T lymphocytes form an antigen-independent ring junction

Abstract

Immunological synapses are organized cell-cell junctions between T lymphocytes and APCs composed of an adhesion ring, the peripheral supramolecular activation cluster (pSMAC), and a central T cell receptor cluster, the central supramolecular activation cluster (cSMAC). In CD8+ cytotoxic T lymphocytes, the immunological synapse is thought to facilitate specific killing by confining cytotoxic agents to the synaptic cleft. We have investigated the interaction of human CTLs and helper T cells with supported planar bilayers containing ICAM-1. This artificial substrate provides identical ligands to CD4+ and CD8+ T cells, allowing a quantitative comparison. We found that cytotoxic T lymphocytes form a ring junction similar to a pSMAC in response to high surface densities of ICAM-1 in the planar bilayer. MICA, a ligand for NKG2D, facilitated the ring junction formation at lower surface densities of ICAM-1. ICAM-1 and MICA are upregulated in tissues by inflammation- and stress-associated signaling, respectively. Activated CD8+ T cells formed fivefold more ring junctions than did activated CD4+ T cells. The ring junction contained lymphocyte function associated antigen-1 and talin, but did not trigger polarization and granule translocation to the interface. This result has specific implications for the mechanism of effective CTL hunting for antigen in tissues. Abnormalities in this process may alter CTL reactivity.

Authors

Kristina Somersalo, Nadja Anikeeva, Tasha N. Sims, V. Kaye Thomas, Roland K. Strong, Thomas Spies, Tatiana Lebedeva, Yuri Sykulev, Michael L. Dustin

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Figure 2

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The kinetics of and the irrelevant MHCp complex and ICAM-1 density depen...
The kinetics of and the irrelevant MHCp complex and ICAM-1 density dependence of ring junction and contact formation by CTL clones. (a and b) A CER43 cell on a bilayer containing 200 molecules/μm2 Cy3-ICAM-1–GPI alone. (a) Interference reflection microscopy images showing contact development (darker areas represent closer contact). (b) Fluorescence images showing LFA-1–ICAM-1 interaction during ring junction development. Cy3–ICAM-1 in grayscale (white represents the highest ICAM-1 density). The mean duration of transient ring junctions is 15 minutes, and a cell can make one to four ring junctions within an hour, with intervening migration. Scale bar: 5 μm. (c) Effect of irrelevant (irrel.) MHCp complexes on ring junction formation. The kinetics of ring junction formation were assessed for populations of CER43 cells on 200 molecules/μm2 Cy3–ICAM-1–GPI (filled diamonds) or 40 molecules/μm2 irrelevant Alexa 488-HLA-A2–IV9 (open diamonds). Ring junction formation reached a steady state within 15 minutes. No significant difference was detected without or with irrelevant MHCp complexes. (d) Percentage of ring junction formation by CTL clone 68A62 as a function of ICAM-1 density in the absence (filled circles) and presence (open squares) of 100 nM MICA on bilayers containing 50% Ni2+/NTA lipids. (e) Percentage of adhering 68A62 CTL clone cells as a function of ICAM-1 density in the absence (filled circles) and presence (open squares) of 100 nM MICA on bilayers containing 50% Ni2+/NTA lipids. Data in d and e are representative of data for 68A62 and CER43 CTL clones. In each case, over 1,000 cell contacts were analyzed to generate the graphs.