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New Blood Test for Peanut Allergy More Accurate


Peanut allergy is one of the most common food allergies in children. Recent reports suggest that peanut allergy is on the increase. Peanut allergy tends to be lifelong, can be severe, and in extreme cases fatal.

Clinicians and scientists at University Hospital South Manchester, the University of Manchester, and Phadia AB in Uppsala, Sweden have developed a new blood test for peanut allergy, which predicts whether an allergic reaction to peanuts will develop with more than 95 per cent certainty.

Professor Adnan Custovic and colleagues examined the prevalence of peanut allergy in 933 eight year old children 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.

The study findings, published in the January issue of Journal of Allergy and Clinical Immunology, 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 identify those children at real risk. The researchers challenged children with suspected peanut allergy with peanuts in a safe, controlled environment.

It was found that 80% of the children who were previously thought to have an allergy test did not suffer a reaction to the peanuts. Most of them had hay fever and were in fact allergic to grass or tree pollen.

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The new blood test detects antibodies to the peanut protein RH2 and was accurate in 97% of cases.

It meant only one in 50 of the children were truly allergic to peanuts on the basis of the oral peanut challenge compared to previously the figure was as high as one in ten.

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 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 test 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 advice on treatment will be a major step forward in management of patients with peanut allergy".

Allergy or tolerance in children sensitized to peanut: Prevalence and differentiation using component-resolved diagnostics; Journal of Allergy and Clinical Immunology Volume 125, Issue 1, Pages 191-197.e13 (January 2010); Nicolaos Nicolaou, Maryam Poorafshar, Clare Murray, Angela Simpson, Henric Winell, Gina Kerry, Annika Härlin, Ashley Woodcock, Staffan Ahlstedt, Adnan Custovic



It is not RH2, the protein is Ara h 2. Arachis hypogaea is the scientific name, and that is how the protein names are derived. First 3 letters + first letter + order of discovery Ara h 2 See allergome.org for more details.