Food and diet

Research into peanut allergy treatments

“Peanut allergy cure ‘available by 2013’” reads the headline in The Daily Telegraph . The newspaper reports that research is being carried out on ways to “dampen the faulty immune reaction to the nuts, which could avoid the fatal side effects of eating peanuts”. They say that “a cure” may be available in five years’ time.

This news story is based upon a narrative review that discusses the change in the prevalence of peanut allergy over recent decades and discusses the importance of recognising the symptoms and implementing avoidance strategies. The article discusses potential new treatments that are under development, but these are currently some way off. It is somewhat suprising to suggest to sufferers and their families that a complete cure will be available by 2013.

Where did the story come from?

This author of this research is Professor A. Wesley Burks, who received funding from Allertein Inc., Danone, Dey, SHS International, McNeil Nutritionals, Novartis, the US National Institutes of Health, the Food Allergy and Anaphylaxis Network, the Gerber Foundation, the Mead Johnson company and the Food Allergy Project. The study was published in The Lancet , a peer-reviewed medical journal.

What kind of scientific study was this?

This was a narrative review where the author discusses the causes, pathology, diagnosis and management of peanut allergy, following a literature search of Medline and the Cochrane Library for all publications over the past five years related to peanuts and allergies. The author also looked at reference lists from identified articles.

The allergy affects approximately 1% of children under the age of five years and caused by an immune response triggered when susceptible individuals are exposed to peanuts. The review reports the findings of several studies about nut allergy. A population study in the UK found that the prevalence of peanut ‘sensitivity’ among three-year-old children rose from 1.3% in 1989 to 3.2% in 1995. Certain people can also have allergies to other nuts, fish, shellfish, milk, wheat, eggs or soy. Food allergies can cause various degrees of response from inflammation and itching of the skin or stomach upset, to severe swelling of the eyes, lips, mouth and tongue, blockage of the air passages and circulatory collapse, i.e. anaphylaxis. Reactions can be immediate (seconds) or delayed for several hours. Susceptible individuals can be affected by only a few milligrams of peanut protein.

The author discusses the complex pathophysiology of how the immune response occurs in the body. He says that in 75% of cases of peanut allergy, symptoms develop after first exposure, typically at about 14 months of age. He says that diagnostic history taking should include detailed questions on the symptoms experienced, the timing of ingestion, the quantity of peanut taken and experiences with similar foods. Both skin-prick allergy testing and the interpretation of its results should be carried out with caution, in light of the individual case.

There should be a written management plan, including patient and family education. This should involve how to avoid ingestion of all potentially triggering substances (e.g. reading all food labels), how to recognise and manage early stages of a reaction (e.g. use of an self-injectable adrenaline pen where appropriate), alerting people in other environments (e.g. wearing alert bracelets, telling teachers and catering staff in schools etc.) and arranging long-term follow-up. The author also discusses acute hospital management of anaphylaxis.

Regarding new developments and future treatments to prevent the rise in the prevalence of peanut allergy, the author says there are several possibilities. One is to develop genetically altered plants that produce non-allergy-causing peanuts. Another is to identify the biological markers of the disease that occur in people who experience anaphylaxis and these could provide a possible genetic test for predicting the disease and its severity. There are also new immunotherapies currently under development (of a number of different types, acting in different ways), which modify the body’s immune response.

What were the results of the study?

Immunotherapy experiments using engineered peanut allergens have been carried out in animals that have been genetically sensitised to peanuts, to see whether the immune response can be ‘dampened’. After mice were treated with a heat-treated bacteria that contained the mutated nut protein, they found that symptoms upon subsequent exposure to nuts were reduced compared with the control mice. In addition, the production of immune markers was less in these mice.

Other approaches, which do not include exposure to an allergen, have been tested. One has been trialled involving injecting anti-human IgE (IgE being the main antibody involved in allergic reactions). However, results from this have been inconclusive and it may only have a role as an adjunct to other treatments.

Other studies are ongoing to see whether it is possible for immunotherapy to be administered in an alternative way to the usual subcutaneous injection, e.g. under the tongue or ingested.

With all immunotherapy involving administration of the allergen in some form, there is always a risk of anaphylaxis during therapy.

What interpretations did the researchers draw from these results?

The author says that treatment with the mutated peanut proteins “could induce long-term down-regulation of peanut hypersensitivity”. Taken as a whole, recent studies raise the possibility of ”at least raising the threshold of the amount of peanut that it would take to cause a life-threatening allergic reaction”. He says there is likely to be some form of immunotherapy available for those with peanut allergies in the next five years.

What does the NHS Knowledge Service make of this study?

This study is a narrative review on peanut allergy following a search for published literature on the subject. The search identified a few studies relating to immunotherapy, some animal and some human. Although it is clear that treatments are under development, as the author says  “whether these types of treatment are likely to cause eventual clinical tolerance remains to be seen”. It is somewhat suprising to suggest to sufferers and their families that a complete cure will be available by 2013.

Sir Muir Gray adds...

The rise of allergies is one of the great challenges and mysteries of our time; the opinion of an expert can help us have an overview of a problem with his judgement being combined with best current evidence.

NHS Attribution