Friday February 20 2009
People should not try to replicate the process at home as it may prove fatal
“Children with severe peanut allergies have been cured,” The Daily Telegraph reported. This was one of several newspaper articles reporting on a study of a treatment to make four allergic boys less sensitive to peanuts.
Scientists started by giving the children tiny doses of peanut flour each day, slowly increasing the amount over six months until the children could eat the equivalent of five peanuts. In the Daily Express one lead researcher stresses “it is vital parents do not try this at home with their children”, as “it can only be safely tried under strict medical supervision”.
This small study has shown that it is possible to reduce peanut sensitivity in children who have peanut allergies. It is important to note that these children have not been cured, rather that their tolerance of peanuts has increased. It is also likely that they will need a long-term programme of maintenance treatment to retain these improvements.
Further trials are reportedly aiming to replicate the process in a larger group of children, and further studies are needed to determine whether a similar treatment can work in adults.
It is crucial that people do not attempt to reduce their own sensitivity or that of their children as severe allergic reactions are potentially fatal.
Where did the story come from?
This research was conducted by Dr Andrew T. Clark and colleagues from the Cambridge University Hospitals NHS Foundation Trust at Addenbrooke’s Hospital. The study was funded by the Evelyn Trust, Cambridge, with the Golden Peanut Company providing materials for the study. It was published in Allergy, a peer-reviewed medical journal.
What kind of scientific study was this?
This was a case series, looking at the effects of a peanut oral immunotherapy (OIT) in children with peanut allergies. Immunotherapy is a treatment strategy that aims to alter the immune system so that it becomes desensitised (no longer sensitive) to the substance that normally causes the allergic response (the allergen). Immunotherapy strategies, most involving injection of increasing amounts of the allergen over time, have been developed for other allergies, such as those to bee stings.
With the agreement of their families, four boys age nine to 13 were enrolled into the study. All had suspected peanut allergies, and two of the boys had previously experienced reactions after accidental exposure to peanuts.
The researchers used a skin prick test to confirm that the boys had a peanut allergy. This process involves pricking the skin, applying a small amount of peanut extract to the pierced area and looking for a reaction. The researchers also carried out blood tests to look for an immune response to exposure during the skin prick test, and then exposed the boys to peanut flour and a placebo substance in a double-blind test to determine how much peanut it took to give each boy an allergic reaction. These tests were carried out both before the start of the study and at the end of the study.
In these tests, the children were given doses of peanut protein ranging from one to 100mg on separate days. If the boys showed no reaction to these amounts, they were to be given up to 12 whole peanuts and observed for a reaction.
During the treatment phase of the study, all the children were provided with a personalised treatment plan outlining their own OIT daily dosing schedule. Their starting dose was based on their tolerance level, determined through initial tests and the perceived severity of their allergy. Doses were given as peanut flour (half of which was peanut protein) mixed in yoghurt. Doses were roughly doubled every two weeks up to a maximum of 800mg peanut protein, and this daily dose was then maintained.
Six weeks after the final increase in dose, the boys were tested with about 12 whole peanuts, containing about 2.4-2.8g of peanut protein. After this, participants could continue to take 800mg of peanut protein daily as a maintenance dose, either in the form of peanut flour (1,600mg), smooth peanut butter (about 2.5ml) or five whole roasted peanuts.
All of the double-blind testing and dose increases were carried out in the Wellcome Trust Clinical Research Facility, and the children were watched for two hours. Once a dose had been successfully increased, the children took the doses at home for two weeks. All families were provided with oral antihistamines and adrenaline injections for their child, which could be used to help treat any allergic reaction that might have occurred.
What were the results of the study?
Skin prick testing confirmed the four children to have peanut allergies. In tolerance testing at the start of the study, the children showed allergic responses to between five and 50mg of peanut protein, which equates to just a fraction of the approximately 200mg of protein found in a whole peanut.
Three of the boys’ allergic reactions could be treated by taking antihistamine tablets (allergy medication), but one boy went into anaphylactic shock and had to be given an adrenaline injection, plus inhaled and injected steroids to stop swelling in his airways and allow him to breathe.
During the peanut immunotherapy, the researchers managed gradually to increase the amount of peanut protein that the children could tolerate from 50mg or less at the start of treatment up to 800mg. None of the boys experienced an allergic reaction to the treatment that was severe enough to require an adrenaline injection, although some experienced mild symptoms such as abdominal pain when doses increased.
After the treatment, all children could eat between 10 and 12 peanuts (2.4-2.8g). This represented an increase of between 48 and 478 times in their tolerance of peanuts compared with the start of the study.
What interpretations did the researchers draw from these results?
The researchers conclude that oral peanut immunotherapy was well tolerated, and resulted in substantial increases in the amount of peanut that could be tolerated by all of the children. They say that the children were protected against doses of at least 10 peanuts, which is more than the children would be likely to eat by accident.
Although these results are encouraging, the researchers say the treatment should not yet be tried outside clinical trials.
What does the NHS Knowledge Service make of this study?
This small study proves that it is possible to use immunotherapy to reduce sensitivity to peanuts among children with peanut allergies, even if their allergy is severe. Further trials are reportedly underway to see whether success can be replicated in a larger group of children.
These findings are likely to bring hope to parents of children with peanut allergies. However, it is vital that people do not attempt to replicate this treatment at home, as severe allergic reactions can be fatal if not treated immediately.
In this research, all of the tolerance tests and dose increases during treatment were carried out in a research facility with the children under medical supervision to ensure that they could receive specialist medical treatment immediately if they experienced a severe allergic reaction (anaphylaxis).
It is also important to note that the main aim of these treatments is to avoid severe allergic reactions in children who are accidentally exposed to peanuts. Studies are needed to determine how long and how frequently maintenance immunotherapy must be given to maintain peanut tolerance in these children. Studies will also be needed to determine whether a similar treatment can work in adults with peanut allergies, or people with allergies to other nuts or foodstuffs.