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5 December 2013 11:26 am ,
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An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Assisted Suicide May Help Transplants Survive
4 March 1998 7:00 pm
Transplanted organs rarely get a hero's welcome in their new home--in fact, they are often attacked viciously by the host's immune system. Researchers have long known that a follow-up infusion of bone marrow cells from the same donor eases the transition, but they haven't known why. Now a report in this month's issue of Nature Medicine may provide an explanation: A key bone marrow protein causes immune cells in mouse transplant recipients to self-destruct. The work could eventually lead to new drugs designed to selectively kill those immune cells that have identified a transplant as foreign.
Scientists have known about the beneficial effects of bone marrow transplants since the late 1960s, but "there really hasn't been much data available to explain what is going on," says immunologist James George of the University of Alabama, Birmingham, an author of the new study. Some researchers believe the infused cells simply provide enough foreign matter to desensitize the recipient's immune system to the donor tissue. Others, including George, suspect that donor marrow is more like a benevolent assassin--triggering the suicide of T cells that attack a transplanted organ.
The T cell's self-destruct program is turned on when a molecule on its surface, called Fas, binds to a protein called Fas ligand. Bone marrow cells have such ligands, so George and co-workers set out to see if they are involved in an assisted cellular suicide that helps organ transplants. With researchers at the Jackson Laboratory in Bar Harbor, Maine, George and colleagues transplanted mouse skin to 19 mice. They destroyed the T cells in 12 mice, five of which received marrow cells from normal mice while seven received marrow from mice with a defective Fas-ligand gene. After 50 days, the skin graft survived only in the five mice given normal bone marrow. Controls and mice with defective Fas-ligand marrow both rejected the graft after about 40 days.
"I think they have a very interesting observation," says University of Toronto immunologist Richard Miller. "Those infused bone marrow cells must play an active role." George says his team hopes the findings will someday lead to safer, more effective transplants: "If we could successfully induce tolerance in patients, the result would be a very large improvement in their quality of life."