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Killer T cells on autopilot
How do immune cells become armed killer cells capable of protecting us from invading microorganisms? Current thinking is that the "helper" T cells of the immune system, which orchestrate the immune response, are required to stimulate precursors of other T cells so that they develop into lethal killer T cells. However, two papers in the May issue of Nature Immunology (Vol. 2, No. 5, 01 May 2001) show that this may not actually be the case. Researchers from Stephen Schoenberger's group in San Diego, CA and Rafi Ahmed's group in Atlanta, GA have shown that that helper T cells are not necessary for activating killer cells. Instead, these killer cells are preprogrammed: in the absence of any "help", a brief encounter with peptide from the pathogen is sufficient to turn the cells into killers. Both labs used mouse models of infection and found that with just a short exposure to foreign antigen and no help in sight, inexperienced killer cells began their developmental cycle. This cycle consists of multiple rounds of cell division and the acquisition of all the molecules and functions necessary for these killer T cells to destroy their targets. A pool of these killer T cells become long-lived "memory" cells - an important development, as these are the cells that make vaccinations successful - ready to be reactivated at any time. This data will cause a revision to current thinking about what antigen alone can achieve. As Pamela Fink and Michael Bevan, authors of a News & Views on these findings, say: "Today we are left to deal with the idea of antigen-triggered … T cells running on autopilot". CONTACT: Rafi Ahmed
Emory University
School of Medicine
Department of Microbiology and Immunology
1510 Clifton Road
Atlanta, GA 30322
U N I T E D S T A T E S
Tel: (+1) 404-727-4700
Fax: (+1) 404-727-3722
ra@microbio.emory.edu Stephen P. Schoenberger
La Jolla Institute for Allergy and Immunology
Division of Immunoregulation
10355 Science Center Drive
La Jolla, CA 92121
U N I T E D S T A T E S
Tel: (+1) 858-678-4574
Fax: (+1) 858-558-3525
sps@liai.org Michael J. Bevan University of Washington
Howard Hughes Medical Center
Department of Immunology
I-604F Health Sciences Bldg
Box 357370
Seattle, WA 98195
U N I T E D S T A T E S
Tel: (+1) 206-685-3610
Fax: (+1) 206-685-3612
mbevan@u.washington.edu (C) Nature Immunology press release.
Message posted by: Trevor M. D'Souza
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