title: Involvement of FK506-sensitive and insensitive granule exocytosis pathways in perforin-dependent target cell lysis mediated by a CD8+ CTL clone.
abstract: The release of granzyme A and B through granule exocytosis by CD8+ CTL clone OE4 upon T cell receptor (TCR) activation was blocked by FK506 in a dose-dependent manner (IC50 = 3 nM), whereas a significant granzyme release was still detectable even in the presence of excess FK506. In contrast, the production of IFN-gamma was highly sensitive to FK506 (IC50 = 0.01 nM) and could be completely blocked by FK506. Both FK506-sensitive and insensitive granule exocytosis pathways were involved in the actual perforin-dependent killing toward different target cells. The combination of ionomycin and phorbol ester was able to mimic TCR stimulation to induce IFN-gamma production, although the same treatment triggered granule exocytosis inefficiently. Granule exocytosis and IFN-gamma production following TCR activation were profoundly prevented by calphostin C. Thus, these results demonstrate that the granule exocytosis pathway in this CD8+ CTL clone depends on the activation of protein kinase C, and requires either calcineurin-dependent or independent additional signals downstream of TCR activation.
authors.affiliation: Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan. tkataoka@bio.titech.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Kataoka
authors.forename: K
authors.initials: K
authors.lastname: Nagai
mesh_terms: D000818:Animals; D015550:Cell Degranulation / Q000187:drug effects*; D003602:Cytotoxicity, Immunologic; D005089:Exocytosis / Q000187:drug effects*; D053804:Granzymes; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007371:Interferon-gamma / Q000096:biosynthesis; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D051379:Mice; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012697:Serine Endopeptidases / Q000378:metabolism; D015398:Signal Transduction; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism; D016559:Tacrolimus / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D007166:Immunosuppressive Agents; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D007371:Interferon-gamma; D053804:Granzymes; C509214:Gzmb protein, mouse; D012697:Serine Endopeptidases; D016559:Tacrolimus