A study at Duke University, North Carolina found that five out of seven children with severe peanut allergy were able, after two years of immunotherapy, to tolerate a dose of 7.8 grams of peanut flour, equivalent to eating more than 13 peanuts.

The children, who all had a convincing clinical history of peanut allergy were fed, over one day, increasing multiple doses of peanut flour (mixed in a food of choice, such as apple sauce), with doses escalating from 0.1mg to 25mg, or, if tolerated, to 50mg. About half of the patients were able to tolerate the 50mg dose by the end of the day; the remainder were able to tolerate either 12.5 or 25mg, said Dr Scott Nash who was leading the study.

The children then went home and remained on their current dose daily, returning to the centre every two weeks for a dose increase until they reached a dose of 300 mg, equivalent to about one peanut. Parents were asked to keep a daily diary of symptoms.

The children remained on 300mg of peanut flour daily for two years, before returning to the centre for a food challenge of up to 7.8g of peanut flour, equal to a good adult-sized handful of nuts. The challenge was delivered in escalating doses beginning at 600mg every 30 minutes up to the maximum.

In all, five of seven children had no reaction on the food challenge. One child took the full dose, but 90 minutes later had a reaction that required epinephrine. The remaining child made it to 4,200 mg, and then required epinephrine for cough and hives.

The researchers also looked at immunologic characteristics of food allergy, and found that peanut-specific IgE and IgG both rose initially and then fell during the study, while peanut-specific IgG4 increased throughout the study.

‘We think that our patients are now at decreased risk for anaphylaxis if they accidentally eat peanuts but we're not recommending that they reintroduce peanuts into their diet.’ said Dr Nash. Dr Nash also cautioned patients that oral immunotherapy should not be attempted at home, and should only be performed under the close supervision of a physician because of the risk of anaphylaxis.

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Courtesy of the Anaphylaxis Campaign - www.anaphylaxis.org.uk

Meanwhile, Dr Andrew Clark and Sr Yvonne King at the Welcome Trust laboratories at Addenbrooke’s Hospital are recruiting children of seven and over with peanut allergy to take part in an immunotherapy trial.

Each child will undergo a peanut challenge and will then go to Cambridge on a regular basis to be fed tiny doses of peanut, increasing over time. At the end of the trial they will undergo a further peanut challenge.

Anyone interested in having their child take part in the trial should contact Dr Andrew Clark - atclark@doctors.org.uk / 01223 762603
Box 40, Addenbrookes NHS Foundation Trust, Cambridge CB2 2QQ

First published in January 2008

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