PEANUT
ALLERGY CURE
“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 recognizing 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
surprising 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.
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 immunotherapy currently under development (of a number of
different types, acting in different ways), which modify the body’s immune
response.
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 were the
results of the study?
Immunotherapy
experiments using engineered peanut allergens have been carried out in
animals that have been genetically sensitized 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.
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 surprising to suggest to sufferers and their
families that a complete cure will be available by 2013.
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 recognize 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.
Other
approaches, which do not include exposure to an allergen, have been
tested. One has been trialed 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.
