peanut allergies

Xolair, an antibody asthma drug, was recently approved for severe food allergic reactions. It is not the first biological drug to treat multiple conditions. But it is the first to treat severe food allergies - a growing problem.
Does our immune system act as a defensive barrier, or a translator of different worlds? Is there a mismatch between our genetic heritage and our current environment? And can being less "clean" make us more healthy? Let's find out.