USDA researchers find peanut variety missing major allergen

WASHINGTON -- At potlucks, Joe Craighead sniffs the casseroles, stews, salads and pastas before taking a bite. Whenever he shops for groceries, he examines the ingredients on the back of the package before putting it into his cart.

Craighead is looking for peanuts. His body responds to them as if they were a poisonous invader. His mouth and palms become irritated, his eyes itch and his, throat constricts. He inhales and exhales faster and faster -- all part of a horrible allergic reaction.

"Often with peanut allergies, people say, 'You'll just have hives or something,'" said Craighead, 53, of Denver. "I have to explain that maybe this would be life or death."

Craighead is one of 1.5 million Americans who are allergic to peanuts and products such as peanut butter. For many of these people, the Agriculture Department may have found a solution -- a special peanut that lacks one of the major allergens, a protein known as Ara h 2, or conglutin-homologue.

Soheila Maleki, a biochemist at the Agriculture Department's research center in New Orleans, led the recent discovery of NC 4, a natural variety of peanut without the conglutin-homologue protein.

To find it, Maleki and a team of scientists screened 300 natural peanut varieties grown from seeds kept in a national germplasm collection at North Carolina State University. The scientists checked the peanuts for Ara h 2 using antibodies taken from rabbits.

The search for a natural, hypoallergenic peanut is a unique approach. Other researchers are trying to deactivate the allergens in peanuts through genetic engineering or develop new medicines for treating peanut allergies.

Anyone who wants to grow the peanut NC 4 can obtain it from the university's collection, Maleki said.

14,000 kinds

Maleki said her project is not over. She and her team are screening peanut varieties in search of one that is missing the other leading allergen, vicilin. Once they find it, they will breed it with NC 4 to create a pure hypoallergenic peanut.

The objective is to give food manufacturers a peanut that could replace the common ones found in products like mixed nuts and peanut butter.

"We're hoping that while we may not be able to cure these people, we can make it so that if they have an accidental ingestion, it won't be fatal," Maleki said.

Because there are 14,000 varieties of peanuts, finding one without the vicilin allergen could take a decade, she said.

Peanut growers also recognize that new treatments and hypoallergenic products could help them reach more consumers.

Unlike Craighead and the 1.5 million others like him who are allergic to peanuts, most consumers do not know that peanut butter is often used as a thickener in foods like spaghetti sauce, barbecue sauce, stew, gravy and chili, or as a paste that prevents pastries and egg rolls from unfolding.

Dr. Donald Y.M. Leung, an expert at the National Jewish Medical and Research Center in Denver, said that even if a peanut lacking the two major allergens is developed, some people may have an allergic reaction. Other allergens affecting far fewer people may still be present.

Other developments are on the horizon, Leung said. One is a drug that raises an allergy victim's tolerance for peanuts. The drug has passed key human tests. Federal regulators have agreed to accelerate the process to judge its fitness for widespread use. Further testing, however, was put on hold last month because of a legal dispute between the drug's maker, Tanox Inc., and its business partners, Genentech Inc. and Novartis AG.

Genentech also has an asthma drug, Xolair, which some researchers believe could treat peanut allergies; no trials using it for that have been conducted.

The NC 4 peanut is a little utilized variety, compared with Valencia and Spanish peanuts. And the other developments are still in their infancy. For now, allergists warn, people allergic to peanuts should still avoid them.

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On the Net:

USDA Agricultural Research Service: http://www.ars.usda.gov