Saturday, November 22, 2008

Repeated Bee Stings Calm Immune Response

A Sting a Day Keeps the Allergy Away
By Ewen Callaway, New Scientist, 11/18/2008

Beekeepers faced with daily stings in their work are helping researchers understand why some people are prone to occasionally deadly allergic reactions, while others are not.

High doses of bee venom early in the year block a normally potent immune reaction for the remainder of the season, says Mübeccel Akdis, an immunologist at University of Zurich in Switzerland, who led the study.

The finding could help in treating the roughly 2% to 5% of people who develop severe allergies to bee stings.

Akdis' team followed a group of beekeepers for several years to determine how their immune systems managed the feat. None of the keepers donned protective masks or gloves while handling the bees.

Venom injection

In late April, the beginning of the season in Switzerland, keepers showed visible signs of an immune response to the stings on their skin, including inflammation and swelling. Within a week, their immune system had muzzled this response, only for it to return the following year after the winter break.

After an average of 13 stings a week, beekeepers quickly desensitise to the bees' barb, which delivers a large dose of several venoms, including a membrane-busting protein called phospholipase A.

The keepers' secret turned out to be the production of cells that dampen the immune attack, called regulatory T-cells.

The first bee attacks of the season trigger the production of histamine, a chemical that drives allergic reactions. But as the beekeeper is further stung, a class of T-cell that would normally boost the immune response against the venom instead senses the histamine and morphs into regulatory T-cells, calming the immune response…

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