INSULIN itself is the target of the friendly fire from the immune system that causes juvenile-onset diabetes.
It has long been known that type 1 diabetes occurs when the immune system mistakenly views insulin-producing cells in the pancreas as foreign and destroys them. But exactly which molecule is the target of this attack has remained uncertain.
Now a team led by George Eisenbarth of the University of Colorado Health Sciences Center in Denver has genetically engineered diabetes-prone mice to produce a modified form of the insulin protein. These mice do not develop diabetes, suggesting that insulin is the target (Nature, vol 435, p 220).
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More evidence comes from another study in the same issue (vol 435, p 224). David Hafler’s team at Harvard Medical School found large numbers of insulin-recognising immune cells in pancreatic lymph nodes in diabetic but not in non-diabetic people. Eisenbarth hopes it might some day be possible to retrain the immune system of people with the disorder so that they can tolerate insulin.
