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Peanut allergy treatment may offer protection but may not be a cure

Wednesday 30 October 2019

"Peanut-allergy therapy 'protection not a cure'," reports BBC News.

Peanut allergy can be life-threatening, and affects about 2% of school children in the UK. The only way to manage a severe peanut allergy is to completely avoid peanuts, and to carry emergency medicine, such as an auto-injector, to treat reactions after any accidental contact with peanut.

Immunotherapy involves taking pills with very small amounts of peanut, in an increasing dose under medical supervision. If the treatment is successful, people have a higher "threshold" for allergic reaction, meaning they are less likely to have a severe reaction if they accidentally eat peanut.

In a new small study, researchers looked at plasma produced by mast cells (cells that can trigger an allergic reaction) in people with peanut allergies who were treated with immunotherapy. The results showed that these people remained allergic to peanuts, but that they produced antibodies during treatment that dampened down the effects of the allergic reaction.

The researchers say this means people are only protected while continuing with treatment, but as this was a proof of concept study (a study to see if a method or idea is correct), we cannot tell for sure.

Where did the story come from?

The researchers who carried out the study were from Kings College London, Queen Mary University of London, Addenbrookes Hospital, all in the UK and Baylor College of Medicine in the US. It was funded by the Medical Research Council and the National Institute for Health Research.

The study was published in the peer-reviewed Journal of Allergy and Clinical Immunology.

The story was reported on Mail Online and BBC News. Both reports appeared balanced and accurate.

What kind of research was this?

This was an experimental laboratory-based study. It used cells from the blood plasma of people who had been treated with peanut immunotherapy in a previous study. This type of study is useful to see what is happening at a cellular level before and after treatment. It helps researchers see how a treatment is working, rather than just whether it seems to be working.

What did the research involve?

In the first study, 22 people aged 4 to 18 with moderate to severe peanut allergy were given tiny, then increasing, doses of peanut, under medical supervision so they could be treated if they had allergic symptoms. By the end of the study they were eating the equivalent of 4 to 5 peanuts a day. They then continued on this "maintenance" dose.

For this study, researchers took blood samples from 14 of these patients. They used plasma from the blood and looked in particular at mast cells, which initiate the allergic reaction. They carried out tests from samples before and after treatment.

In one set of tests, the mast cells were "washed" to remove antibodies around them, before being exposed to peanut. In the second, the mast cells were tested with the antibodies still in place. This was to find out whether the mast cells themselves had changed in the way they reacted to peanut, or whether the presence of antibodies was what allowed people to tolerate small amounts of peanut.

What were the basic results?

The researchers found that mast cells washed of antibodies reacted to peanut in the same way, whether the samples were before or after treatment.

However, after treatment, the mast cells which still had antibodies in place reacted much less to the peanut than the pre-treatment mast cells.

This suggests that the antibodies produced during treatment are the key to its success, and that the underlying allergy is still in place. This means people may need continuing treatment to keep producing the protective antibodies.

How did the researchers interpret the results?

The researchers said peanut immunotherapy "induced blocking antibodies that suppressed mast cell activation … but did not change the functional characteristics of allergen-specific IgE" (an antibody that is involved in allergic reaction and is found on the mast cells).

They added: "A better understanding of the mechanisms underlying the patient's clinical response to treatment will help address the question of whether OIT (oral immunotherapy) induces long-term oral tolerance and help in the decision of whether treated patients can eat the food to which they were previously allergic … or need to follow a specific OIT regimen in the long term."

Conclusion

Immunotherapy may offer help to people with life-threatening allergies, lowering their sensitivity to peanut so that they are less likely to have a serious allergic reaction to accidentally eating peanut. However, the results of the study suggest that people may need to continue with long-term immunotherapy treatment in order to benefit.

The study has some limitations. It's an experimental study based on very few people. The people in the study had been having immunotherapy for a maximum of 24 months (2 years). It's possible that a bigger study or one involving people who had been on therapy for longer might have found different results.

At present, there is no cure for peanut allergy and most people with peanut allergy have to avoid eating peanuts. Immunotherapy is not offered as a standard treatment on the NHS for peanut allergy because it is still being tested. Most people in the UK who have had immunotherapy for peanut allergy have been part of studies to find out whether it works.

Find out more about food allergies and how to manage them.

Links to the headlines

Peanut-allergy therapy 'protection not a cure'

BBC News, 30 October 2019

Peanut allergy immunotherapy pills do NOT cure patients but can protect them from potentially life-threatening reactions, scientists say

Mail Online, 30 October 2019

Links to the science

Santos AF, James LK, Kwok M, et al.

Peanut oral immunotherapy induces blocking antibodies but does not change the functional characteristics of peanut-specific IgE

The Journal of Allergy and Clinical Immunology. Published online 29 October 2019