The actin cytoskeleton and cytotoxic T lymphocytes: evidence for multiple roles that could affect granule exocytosis-dependent target cell killing

• Published in: The Journal of physiology Vol. 547; no. 3; pp. 835 - 847
• Main Authors: Lyubchenko, Taras A, Wurth, Georjeana A, Zweifach, Adam
• Format: Journal Article
• Language: English
• Published: England The Physiological Society 15.03.2003; Blackwell Science Inc
• Subjects: Actin Cytoskeleton - drug effects; Actin Cytoskeleton - immunology; Antibodies, Monoclonal - pharmacology; Antineoplastic Agents - pharmacology; Bridged Bicyclo Compounds, Heterocyclic - pharmacology; Calcium - metabolism; CD3 Complex - immunology; CD3 Complex - metabolism; Cell Membrane - metabolism; Cell Movement - drug effects; Cell Movement - immunology; Depsipeptides; Exocytosis - immunology; Humans; Leukemia; Lymphoma, B-Cell; Membrane Glycoproteins - metabolism; Peptides, Cyclic - pharmacology; Perforin; Pore Forming Cytotoxic Proteins; Research Papers; Signal Transduction - immunology; T-Lymphocytes, Cytotoxic - cytology; T-Lymphocytes, Cytotoxic - immunology; Thiazoles - pharmacology; Thiazolidines; Tumor Cells, Cultured
• DOI: 10.1113/jphysiol.2002.033522
• ISSN: 0022-3751

One important mechanism cytotoxic T lymphocytes (CTLs) use to kill virus-infected, transplanted or tumour targets is exocytosis of granules that contain cytotoxic agents such as perforin and granzymes. Granule exocytosis-dependent target cell killing is a complex process, involving initial T-cell receptor (TCR)-dependent signalling that includes Ca 2+ influx and activation of protein kinase C, shape changes that serve to bind the CTL to the target and, finally, exocytosis of lytic granules at the site of contact with the target cell. Although there is reason to propose that multiple steps in the lytic process could involve the actin cytoskeleton of CTLs, few studies have examined this issue, and those that have do not allow the specific step(s) involved to be determined. We have used the potent membrane-permeant actin cytoskeleton-modifying drugs jasplakinolide and latrunculin A to investigate the actin dependence of defined processes that are expected to be important for granule exocytosis-dependent killing. Our results, obtained using TALL-104 human leukaemic CTLs as a model system, are consistent with the idea that a functional actin cytoskeleton is required for TCR/CD3-dependent signalling, for activation of store-dependent Ca 2+ influx and for CTL shape changes. When cells were stimulated with solid-phase anti-CD3 antibodies, treatment with either jasplakinolide or latrunculin A abolished granule exocytosis. However, when cells were stimulated in a manner that bypasses TCR/CD3-dependent signalling, granule exocytosis was not significantly altered, suggesting that the actin cytoskeleton does not function as a barrier to exocytosis.