It's hard to believe that there's an upside to parasitic worms, but statistics indicate that people who are infested have lower rates of asthma and allergies. A group of Scottish biologists has figured out why.
Rick Maizels at the University of Edinburgh and his colleagues find that the worms manipulate their hosts into producing cells called regulatory T cells, which calm the immune system. "The parasite, for its own benefit, exploits these regulatory cells so that the immune system isn't able to expel it," he says, "but a side effect is that it also dampens the allergic response." With the immune system mellowed, the host's reaction to other foreign objects such as dust mites or dander is much milder. In type 1 diabetes, the body attacks its own cells in the pancreas, limiting their ability to produce insulin; the intestinal worms would most likely clamp down on the immune response ...
