What’s the News: For someone with severe peanut allergies, the tiniest trace of the nut makes their immune system go into overdrive, attacking what it perceives as an intruder so vehemently that the person can go into anaphylactic shock. Scientists may have found a way to calm that immune overreaction, a new study in rats shows, by tacking peanut proteins onto certain immune cells, effectively teaching the whole system that peanuts aren’t a threat.

How the Heck:

• The research team drew blood from mice bred to have a condition much like severe human food allergies: a tiny taste of peanut, and their hypersensitive immune system would ramp up, causing their airways to swell shut.
• From the blood sample, the researchers isolated the leukocytes, white blood cells that help the immune system protect against microbes and other invaders, and attached peanut proteins to the cells’ surface. They then reintroduced each rat’s cells—now with the peanut-protein addition—into its blood stream.
• In people (and rats) with peanut allergies, a particular type of helper T cell, a cell that signals the immune system to attack, sounds the alarm when it comes across a peanut protein. But since peanut proteins were attached to the immune system’s own cells, the T helper cells in these rats learned to tolerate the peanut protein, no longer treating it as a threat.
• Once they’d gotten two doses of the modified leukocytes, the rats ate peanut extract. They didn’t show any serious ill effects, even though a similar snack would have dangerously swollen their airways prior to the transfusions.
• The researchers then did a similar test, with rats bred to be allergic to an egg protein, and got the same result: tacking a bit of the offending molecule onto an immune cell ahead of time meant the rats’ immune system could handle egg protein later.

Not So Fast: The study was in rats, not humans. It will take a lot more testing, and a lot more time, to know whether this sort of treatment will allow people with severe peanut allergies can safely eat foods with trace amounts of peanuts, much less enjoy a PB&J.

The Future Holds: The ultimate goal is, of course, to develop a treatment for people with severe allergies to peanuts or other food. The researchers also hope that tacking on proteins from multiple allergens—say peanuts, egg, and soy—could be used to treat multiple food allergies at once.

Reference: Charles B. Smarr, Chia-Lin Hsu, Adam J. Byrne, Stephen D. Miller & Paul J. Bryce. “Antigen-Fixed Leukocytes Tolerize Th2 Responses in Mouse Models of Allergy.” Journal of Immunology, published online October 5, 2011. DOI: 10.4049/?jimmunol.1100608

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