Journal Article

Comparison of Fas- versus perforin-mediated pathways of cytotoxicity in TCR- and Thy-1-activated murine T cells

Hidefumi Kojima, Masahiro Toda and Michail V. Sitkovsky

in International Immunology

Published on behalf of Japanese Society for Immunology

Volume 12, issue 3, pages 365-374
Published in print March 2000 | ISSN: 0953-8178
Published online March 2000 | e-ISSN: 1460-2377 | DOI:
Comparison of Fas- versus perforin-mediated pathways of cytotoxicity in TCR- and Thy-1-activated murine T cells

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T cell-mediated cytotoxicity can be triggered by cross-linking of TCR or Thy-1 surface proteins. While the TCR-triggered signaling initiates both perforin- and Fas ligand (FasL)–Fas-mediated mechanisms of cytotoxicity, it was not clear which mechanism was utilized by Thy-1-triggered signals and which pathway of cytotoxicity was triggered at low levels of antigen expression. It is shown that glycophosphatidylinositol-linked surface glycoprotein Thy-1 preferentially activates FasL–Fas- but not perforin-mediated cytotoxicity. This is explained by the lesser intensity of Thy-1-mediated signaling in T cells. The data suggest that Thy-1-triggered Fas-mediated cytotoxicity is completely dependent on cross-talk between Thy-1 and TCR signals since mutations in TCR–CD3 complex molecules or inhibition of tyrosine kinases or calcineurin abolished or strongly inhibited Thy-1-triggered FasL–Fas-mediated cytotoxicity. Lower concentrations of antigenic peptide or levels of cross-linking with anti-TCR–CD3 mAb are required to trigger Fas-mediated than perforin-mediated cytotoxicity by different cytotoxic T lymphocyte (CTL) lines and clones, and it is shown that cross-linking of Thy-1 is much less efficient in triggering accumulation of second messengers (intracellular Ca2+) than cross-linking of TCR on CTL. Taken together, these data reflect the possibility of differential activation of FasL and/or perforin pathways of cytotoxicity depending on the nature of activating stimuli and surface receptor.

Keywords: cytotoxic T lymphocyte; Fas ligand; perforin; retargeting; TCR; Thy-1; CTL cytotoxic T lymphocytes; CsA cyclosporin A; FasL Fas ligand; GPI glycophosphatidylinositol

Journal Article.  7349 words.  Illustrated.

Subjects: Immunology ; Biological Sciences

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