Boston -- A U.S. study is helping explain how allergic reactions are triggered by calcium channels that are essential regulators of mast cell activation.

Researchers at Beth Israel Deaconess Medical Center said their study not only solves a longstanding molecular mystery regarding the onset of asthma and allergy symptoms but provides a fundamental discovery regarding the functioning of mast cells.

A group of immune cells found in tissues throughout the body -- mast cells -- were once exclusively known for their role in allergic reactions, lead author Monika Vig said. In order for mast cells to function, they require a biological signal -- specifically, calcium, said Vig. Calcium moves in and out of the cells by way of ion channels known as calcium-release-activated calcium, or CRAC, currents. Last year, several research groups, including Vig's, identified CRACM1 as being the exact gene that was encoding for the calcium channel.

"With the identification of this long-elusive gene, we were able to create a knockout mouse that lacked CRACM1, and (as predicted) these animals proved to be resistant to various stimuli that usually cause severe allergic reactions," said Vig.

The study appears in the January issue of Nature Immunology.

Copyright 2008 by United Press International.