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A NEW way to treat diabetes is likely following the discovery that diabetic
mice can be cured by retraining their immune systems.

In people, type I diabetes occurs when a fault in the immune system causes it
to attack the islet cells in the pancreas, which produce insulin. Without
insulin, the body is unable to control the level of glucose in the blood. Almost
all type I diabetics regulate their blood sugar with daily injections of
insulin.

Now a team led by Denise Faustman of Massachusetts General Hospital in Boston
has discovered two abnormalities in the immune cells of diabetic mice. First,
some of their T cells do not express proteins called 鈥渟elf-peptides鈥�, which the
immune system uses to tell the body鈥檚 own cells from invaders. Secondly, these
defective T cells appear especially susceptible to a protein called TNF-alpha,
which the body uses to tag tumour cells for destruction.

The team used a drug to induce the body to produce more TNF-alpha and kill
off the defective T cells. When the body began replenishing the T cells, the
researchers injected lymph cells from a donor which did express the
self-peptide. Before being rejected, they retrained the new T cells so that they
no longer attacked islets. Faustman hoped to suppress the immune response
against islets from a donor. Instead, she was surprised to see that the mice鈥檚
own islets began to recover.

In 75 per cent of the mice, enough islet cells grew back for the mice to
maintain normal blood glucose levels. 鈥淚t鈥檚 an exciting, interesting, apparently
top-notch observation,鈥� says Robert Goldstein of the Juvenile Diabetes Research
Foundation International in New York.