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[IP] RE: Diabetes
'Magic Marker' May Have Been Found in Juvenile Diabetes
Immune cell target discovered
By Adam Marcus
MONDAY, Aug. 30 (HealthSCOUT) -- Insulin, the hormone that gives many
diabetics life, is also the substance that imperils them.
So says a new study by U.S. researchers who found that killer immune cells
zero in on the insulin in their search-and-destroy mission against the
The report, published in September's issue of Nature Medicine, could help
researchers develop preventive treatments for people genetically predisposed
to developing diabetes. And experts say it could also benefit patients with
other immune system diseases.
Juvenile onset -- or type 1 diabetes -- affects up to 1 million Americans.
And as its name indicates, the disease most often strikes pre-teen children.
Type 1 occurs when defensive cells, which normally fight off infection,
mistakenly attack the pancreatic tissue that generates insulin, a hormone
that enables the body to exploit glucose.
Eventually, so few of these so-called beta cells (part of the pancreatic
tissue) are left that patients lose the ability to process blood sugar, and
they must replenish their missing insulin or die.
Insulin shots allow type 1 diabetics a normal life, but hormone replacement
is a next-best solution to preventing the immune reaction from occurring in
the first place.
With autoimmune diseases, one approach for prevention is to pacify the
immune system with an incremental introduction of its targets, called
antigens -- much like a wary hound can be calmed with a sniff of friendly
In the latest study, Dr. F. Susan Wong, a Yale University immune system
expert, has advanced the hunt for such a peace offering.
Using mice engineered to suffer from diabetes, Wong and her team found that
a small segment of insulin -- so long as it's accompanied by a specific
immune marker -- is improperly interpreted by CD8 T lymphocytes as hostile.
These "killer" cells normally hunt down viral invaders, but in diabetic mice
they become trained to terminate their "friendly" beta cell cousins instead.
"We would like to be able to find ways of diverting the immune system's
aggressive attack," says Wong.
Such a diversion won't be simple, however, says Wong. Another portion of the
insulin molecule has also been shown to be targeted by yet another cell, the
CD4 lymphocyte; it's a less deadly relative of CD8s. So any therapy would
have to accommodate both immune cells, and possibly others, she says.
What goes wrong?
Why CD8's turn against the body isn't clear, but may be the result of flaws
in the way the immune system trains itself to recognize foreign cells, says
Wong. Usually, over-eager immune cells are deleted. But in diabetes and
other immune disorders, these cells are allowed to remain in the body, she
The National Institutes of Health is already sponsoring a trial using small
doses of oral and injected insulin in healthy children who are genetically
predisposed to type 1 diabetes.
"If you already have the disease and are not making insulin, this won't help
you. This is a way to prevent the disease from occurring," says Dr. Robert
Goldstein, vice president for research of the Juvenile Diabetes Foundation
International, which helped fund the Yale study.
Although type 1 diabetes typically appears at around age 10 or 11, it can
strike at any time, Goldstein says. What's more, many people are genetically
susceptible to the disease, but never get it. Why it erupts when it does,
and in whom, isn't known, he says, but may be the result of either an
internal signal or external trigger, like a virus.
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