A handful of children once severely allergic to peanuts now can munch them without worry. Scientists retrained their bodies to tolerate peanuts by feeding them tiny amounts of the very food that endangered them.

Don't try this on your own. Doctors monitored youngsters closely in case they needed rescue, and there's no way to dice a peanut as small as the treatment doses required.

But it's the first evidence that life-threatening peanut allergies one day may be cured. Immune system tests show no sign of remaining allergy in five children, and others can withstand amounts that once would have left them wheezing or worse, researchers reported Sunday.

Are the five cured? Doctors at Duke University Medical Center and Arkansas Children's Hospital must track them years longer to be sure.

"We're optimistic that they have lost their peanut allergy," said lead researcher Dr. Wesley Burks, Duke's allergy chief. "We've not seen this before medically. We'll have to see what happens to them."

More rigorous research is under way to confirm the pilot study, released at a meeting of the American Academy of Allergy, Asthma and Immunology. If it pans out, the approach could mark a major advance for an allergy that afflicts 1.8 million Americans.

For parents of these little allergy pioneers, that means no more fear that something as simple as sharing a friend's cookie at school could mean a race to the emergency room.

"It's such a burden lifted off your shoulder to realize you don't have to worry about your child eating a peanut and ending up really sick," said Rhonda Cassada of Hillsborough, N.C., whose 7-year-old son Ryan has been labeled allergy-free for two years and counting.

It's a big change for a child who couldn't tolerate one-sixth of a peanut when he entered the study at age 2 1/2. By age 5, Ryan could eat a whopping 15 at a time with no sign of a reaction.

Not that Ryan grew to like peanuts. "They smell bad," he said matter-of-factly.

Millions of Americans have food allergies. Peanut allergy is considered the most dangerous, with life-threatening reactions possible from trace amounts. It accounts for most of the 30,000 emergency-room visits and up to 200 deaths attributed to food allergies each year. Although some children outgrow peanut allergy, that's rare among the severely affected.

There's no way to avoid a reaction other than avoiding peanuts. Those allergy shots that help people allergic to pollen and other environmental triggers reduce or eliminate symptoms - by getting used to small amounts of the allergen - are too risky for food allergies.

Enter oral immunotherapy. Twenty-nine severely allergic children spent a day in the hospital swallowing minuscule but slowly increasing doses of a specially prepared peanut flour, until they had a reaction. The child went home with a daily dose just under that reactive amount, usually equivalent to 1/1,000th of a peanut.

After eight to 10 months of gradual dose increases, most can eat the peanut-flour equivalent of 15 peanuts daily, said Burks, who two years ago began reporting these signs of desensitization as long as children took their daily medicine.

Sunday's report takes the next big step. Nine children who'd taken daily therapy for 2 1/2 years were given a series of peanut challenges. Four in the initial study - and a fifth who finished testing last week - could stop treatment and avoid peanuts for an entire month and still have no reaction the next time they ate 15 whole peanuts. Immune-system changes suggest they're truly allergy-free, Burks said.

Scientists call that tolerance - meaning their immune systems didn't forget and go bad again - and it's a first for food allergy treatment, said Dr. Marshall Plaut of the National Institutes of Health.

"Anything that would enable kids to eat peanuts would be a major advance," Plaut said, cautioning that more study is needed. But "this paper, if it's correct, takes it to the next level. ... That is potentially very exciting."

Arkansas Children's Hospital has begun randomly assigning youngsters to eat either peanut flour or a dummy flour. The study is still under way but after the first year, the treated group ate the equivalent of 15 peanuts with no symptoms while the placebo group suffered symptoms to the equivalent of a single peanut, Burks said.

The treatment remains experimental, Burks stresses, although he hopes it will be ready for prime time in a few years.

And he isn't taking chances with the first five allergy-free kids. They're under orders to eat the equivalent of a tablespoon of peanut butter a day to keep their bodies used to the allergen.

Ryan Cassada says his mom sometimes "hides them in things so she can force me to eat it." Peanut butter cookies are OK, he says, just not straight peanut butter.

The battle is a small price, his mother said: "As much as I can get into him is fine with me. It's huge knowing he won't have a reaction."