Press Release
Embargoed: 00:01 hrs Monday January 11, 2010
SCIENTISTS CRACK PEANUT CODE IN CHILDREN
Clinicians and scientists at UHSM (University Hospital South Manchester), the University
of Manchester, and Phadia AB in Uppsala, Sweden have developed a new and
significantly more accurate blood test for peanut allergy, which predicts whether an allergic
reaction to peanuts will develop with more than 95 per cent certainty.
Peanut allergy is one of the most common food allergies in children, with recent reports
suggesting that it is on the increase. It can be severe - and in extreme cases fatal. Unlike
other food allergies, which appear early in life and are usually outgrown by school age
(e.g. cow’s milk or egg), peanut allergy tends to be lifelong.
Professor Adnan Custovic led the research team which examined the prevalence of
peanut allergy in almost 1,000 eight year olds who belong to the Manchester Asthma and
Allergy Study. This group of children were recruited before they were born and have been
followed up at regular intervals since birth. In this study, children with suspected peanut
allergy were challenged with peanuts in a safe, controlled environment. Research has
shown a huge false positive rate for current standard blood or skin tests for sensitivity to
peanuts. Although approximately 1 in 10 children had positive skin or blood test results to
peanut, on the basis of the oral peanut challenge, only 1 in 50 had peanut allergy.
The findings, just published*, confirm that the majority of children with positive skin or
blood tests to peanut do not have clinical peanut allergy, and describe a new blood test
which accurately identifies those children at real risk.
Professor Adnan Custovic, said: “Avoiding peanuts is the best way of managing allergic /
anaphylactic reactions to peanuts. Complete avoidance is difficult to achieve due to the
widespread use of peanuts in prepared foods, and accidental exposures are common and
may be life-threatening. The fear of possible reaction markedly reduces the quality of life
amongst peanut-allergic patients and their families. However, avoiding peanuts only
makes sense if a child is really allergic.
.
“Parents are often anxious to find out whether their child diagnosed with another food
allergy will react to peanut, or whether siblings of their peanut allergic child have peanut
allergy. The lack of specificity of current tests when used in isolation indicates many
patients will inappropriately be given the diagnosis. The new diagnostic test which
accurately discriminates peanut allergy from tolerance will mean we can target avoidance
to those patients really at risk, and remove the considerable stress that comes from the
many false positive sensitivity tests.
”Patients must be able to receive expert help to determine real allergy to peanuts. New
diagnostic tests combined with expert advise on treatment will be a major step forward in
management of patients with peanut allergy”.
Professor Ashley Woodcock, Head of the National Institute for Health Research (NIHR)
Translational Research Facility in Respiratory Medicine at UHSM commented: “This is just
one example of the sort of translational research for patient benefit that NIHR funding is
now driving”.
*Journal of Allergy and Clinical Immunology January 2010 edition
– Ends –
For more information
Contact Susan Osborne, Director of Communications at UHSM on 0161 291 4972 or
mobile 07836 229208.
The study was also supported by a charitable donation from Jackie and Carl Michaelsen.
Notes to Editors
Methods: Within a population-based birth cohort, the team ascertained peanut
sensitisation by skin tests and IgE measurement at age 8 years. Amongst sensitised
children they determined peanut allergy versus tolerance by oral food challenges. They
used open challenge amongst children consuming peanuts (n=45); others underwent
double-blind placebo-controlled challenge (n=34). They compared sensitisation profiles
between peanut-allergic and peanut-tolerant children using microarray with 12 pure
components (major peanut and potentially cross-reactive components, including grass
allergens).
Results: Of 933 children, 110 (11.8%) were peanut-sensitised. Nineteen were not
challenged (17 no consent). Twelve with a convincing history of reaction(s) upon
exposure, high specific peanut IgE≥15kUa/L and/or positive peanut skin test≥8mm were
considered allergic without challenge. Of the remaining79 children who underwent
challenge, seven had ≥2 objective signs and were designated peanut-allergic. The team
estimated the prevalence of clinical peanut allergy amongst sensitised subjects as 22.4%
(95% CI 14.8%–32.3%). Using component-resolved diagnostics, we detected marked
differences in the pattern of component recognition between peanut-allergic (n=29; group
enriched with 12 allergic children) and peanut-tolerant (n=52) children. The peanut
component Ara h 2 was the most important predictor of clinical allergy.
Conclusions: The majority of children considered peanut sensitised based on standard
tests do not have peanut allergy. Component-resolved diagnostics may facilitate the
diagnosis of peanut allergy.