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 Peanuts are the most common cause of fatal food-induced anaphylaxis,
or severe allergic reaction, and allergy cases among children have
risen sharply in recent years. Britain's Food Standards Agency
estimates up to one in 55 children have a peanut allergy.
In contrast to existing skin-prick and other blood tests that
produce a large number of false positive results, the new diagnostic
has 98 percent specificity, researchers from the Medical Research
Council (MARC) reported on Thursday.
Current tests, in use for decades, are based on looking for
antibodies - but they cannot differentiate between sensitivity and
true food allergy.
As a result, doctors often have to conduct a further round of
testing in which patients are fed incrementally larger doses of
peanut in a controlled hospital setting to confirm their allergy, a
process that can itself trigger anaphylactic shock.
So-called oral food challenges require the presence of an allergist
and specialist nurses and they cost around 1,000 pounds ($1,360) to
conduct. The new blood test is five times cheaper.
Dr. Alexandra Santos, an MRC scientist and paediatric allergist at
King’s College London, who led the research, believes the new test
will not only save money on testing but also reduce by two-thirds
the number of stressful oral food challenges that are needed.
The development of the new test follows advances in science that
allow the detection of biological signals from much small blood
samples than in the past.
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"The technology has evolved. Now we have better ways to look at
immune cells and to see how they respond," Santos said.
The new tests focuses on mast cells, which play a pivotal role in
triggering allergic symptoms, such as skin reactions or constricting
of the airways.
In a study involving 174 children, published in the Journal of
Allergy and Clinical Immunology, Santos and colleagues showed the
new test tracked closely the severity of allergies, with the
worst-affected patients having the most activated mast cells.
The team is now discussing plans for the widespread roll-out of the
test with an unnamed commercial partner. There are also plans to
adapt it to other foods, such as milk, eggs, sesame and tree nuts.
There are currently no approved drugs for peanut allergies, although
two biotech companies - U.S.-based Aimmune Therapeutics and France's
DBV Technologies - are working to develop rival treatments.
Santos said the new blood test could play a role in monitoring
patients' response to such medicines.
(Reporting by Ben Hirschler; Editing by Raissa Kasolowsky)
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