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Cell-mediated cytotoxic mechanisms
1Department of Microbiology, University of Colorado Health Sciences Centre, Denver 80262.
Abstract:
There are two competing, but probably really complementary, models for the mechanism of cell-mediated cytotoxicity. One depends upon contact-mediated transmembrane signaling, and the other on the exocytosis of toxic materials by the killer cell. There is exciting news on both fronts. Transmembrane signaling has been shown to involve the surface molecule Fas/APO-1 on targets and its ligand on cytotoxic T cells. The Fas ligand has been cloned, and is a member of the tumor necrosis factor family. The major cytolytic molecule in the exocytosis pathway is perforin; perforin knock-out mice have been produced, and they display many intriguing abnormalities. It has been a bumper year for cytotoxicologists.
Insights
Two models of cell-mediated cytotoxicity show progress. Fas ligand advances transmembrane signaling, while perforin knock-out mice reveal insights into exocytosis pathways in cell killing.
Area of Science:
- Immunology
- Cell Biology
Background:
- Cell-mediated cytotoxicity is crucial for immune responses.
- Two primary mechanisms are proposed: transmembrane signaling and exocytosis of cytotoxic molecules.
Purpose of the Study:
- To review recent advancements in understanding cell-mediated cytotoxicity mechanisms.
- To highlight key findings in both transmembrane signaling and cytotoxic granule exocytosis pathways.
Main Methods:
- Investigated the role of Fas/APO-1 and its ligand in transmembrane signaling.
- Studied the function of perforin in the exocytosis pathway using genetically modified mice.
Main Results:
- The Fas ligand, a tumor necrosis factor family member, is identified as key in Fas/APO-1 mediated signaling.
- Perforin knock-out mice exhibit significant abnormalities, underscoring perforin's critical role in cytotoxicity.
Conclusions:
- Recent discoveries have significantly advanced the understanding of both major cytotoxicity models.
- These complementary pathways are vital for effective immune surveillance and cytotoxic responses.