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Peanut allergy sufferers 'may have new protection against severe reactions'

By Nina Massey, PA Science Correspondent

People with peanut allergies may have a new way to protect themselves from severe allergic reactions, new research suggests.

A tiny dose of peanut protein under the tongue can offer safe and substantial protection against the allergy, scientists say.

Called sublingual immunotherapy - or SLIT - the treatment sees the minuscule amount of liquefied protein absorbed immediately into the bloodstream.

The aim is to desensitise the immune system to larger amounts of peanut protein.

Published in the Journal of Allergy and Clinical Immunology, the research indicates SLIT could offer patients a safe and effective way to protect themselves from severe allergic reactions or even anaphylaxis.

Author Edwin Kim, assistant professor of medicine at the University of North Carolina School of Medicine, said: "As a parent of two children with nut allergies, I know the fear parents face and the need for better treatments.

"We now have the first long-term data showing that sublingual immunotherapy is safe and tolerable while offering a strong amount of protection."

Over the years, clinician scientists have developed three main immunotherapeutic ways to treat nut allergies - all of them attempting to desensitise the immune system.

According to Dr Kim, around 100mg of peanut protein can trigger a reaction, about the same trace amount people fear can show up in food manufactured in a facility that processes peanuts.

One peanut kernel contains around 300mg.

Dr Kim added the main idea of immunotherapy is to keep people, particularly children, "safe from the small hidden exposures that could occur with packaged foods, at restaurants, and with other food exposures".

With SLIT, instead of having patients ingest peanut protein, doctors place a small amount of peanut protein under patients' tongues, where it is immediately absorbed.

Because it avoids digestion, patients are given much less of the protein - about 0.0002 mg initially.

This amount then increases over the course of months to just 2 mg.

In 2011 the researchers conducted a small study of 18 patients to show that SLIT was safe and effective over the course of one year.

Since then, they followed 48 patients in the SLIT protocol of 2mg daily for five years.

In the study, researchers showed that 67% of these patients were able to tolerate at least 750 mg of peanut protein without serious side effects.

About 25% could tolerate 5000 mg.

Dr Kim explained: "SLIT participants tolerated between 10 and 20 times more peanut protein than it would take for someone to get sick.

"We think this provides a good cushion of protection - maybe not quite as good as OIT - but with an easier mechanism (sublingually) and, as far as we can tell right now, a better safety signal."

Oral immunotherapy (OIT) requires patients to ingest a small portion of peanut protein daily.