Severe peanut allergies may stem from the stomach and gut.
A surprisingly large pool of cells involved in allergic reactions to peanuts resides in the stomachs and small intestines of allergic adults, scientists report March 5 in Science Immunology.
Identifying the gastrointestinal tract as a prime location for allergy molecules is “a huge step forward,” says Cecilia Berin, an immunologist who studies food allergies at the Icahn School of Medicine at Mount Sinai in New York City. Studies on mice hinted that certain immune molecules are made in the gut, but there has been scant evidence of that in people, she says. “This is the first time that we actually see what is happening in the gut” in people with peanut allergies, she says.
The new findings may point to treatments for people with food allergies, estimated to affect between 3 and 6 percent of people in the United States.
The study focused on an elusive, rare antibody called IgE. Usually present in very small numbers in the body, IgE can sense invaders such as parasites and cause massive immune reactions designed to purge the threat. But in people with allergies, the antibody can go rogue and targets harmless substances, such as peanut proteins.
Stomach and intestine tissue from the allergic patients, but not esophageal tissue, was teeming with cells that make IgE, the researchers found. In the stomach, for instance, people without allergies had very few IgE-producing cells. People allergic to peanuts had hundreds of times more, the researchers estimate. “There was so much of it there,” Hoh says. “That’s something we were all really surprised about.”
In many cases, these cells seemed to have morphed from making a different, harmless type of antibody to producing IgE. It’s not clear why these cells might be more likely to make this switch in the guts of people with peanut allergies.
The new analyses also point out similarities among some of the allergic participants’ peanut sensing IgEs: They seem to recognize common parts of the peanut protein. Designer antibodies that could block those troublesome spots, and prevent IgE from getting there first and setting off a reaction, might turn out to be a way to curb peanut allergies.
Article sourced from Science News.