Reversing Peanut Allergy

31 December 2018

Interview with

Pam Ewan, Cambridge Peanut Allergy Clinic

Here's a favourite chosen by Chris Smith from a show we made about allergies earlier in the year. Allergies can vary widely in severity. While some are undoubtedly inconvenient, others can actually be life threatening. Chris Smith and Katie Haylor tackled the topic and first up, Katie went to see 8 year old Dillon, and his mum Maaike. Chris was then joined in the studio by Pam Ewan from the Cambridge Peanut Allergy Clinic.Maaike - When Dillon was about 18 months old he was in the garden with his dad and his brother filling up bird feeders with peanuts and had an immediate reaction which resulted in us ultimately being diagnosed with peanut allergy.

Katie - How does it affect your day-to-day?

Maaike - It becomes the most important thing in your life. It makes your world very small to begin with. It’s huge in its detrimental effect on family life but, luckily, we have the resources and the kind friends and family to make it possible to do lots of normal things.

Katie - Dillion, what’s it like having a peanut allergy?

Dillon - Well, it’s a bit hard because we have to check the labels of most things. And, at like a birthday party, they have a cake with peanuts and I have to just deal with it and not have it.

Chris - And we’ll hear a bit more from Dillon and Maaike, later in the programme. But first we’re joined by Pamela Ewan. She is a consultant allergy specialist at the Cambridge Peanut Allergy Clinic and she treats people just like Dillon.

Chris - Why are those allergies so severe Pam?

Pam - Well, no-one really knows why peanut allergy is so severe, but of the foods it’s the one that is the worst so it’s the most common of the foods to cause very severe, sometimes fatal reactions. So it’s a very bad one.

Chris - What age does it tend to kick in at?

Pam - The average age is around two for the first symptom in a child but it could occur at any age and, obviously, that depends a bit on exposure. If you don’t start eating peanuts until you’re older, which is what happens now, probably that age of two is going to go up quite a lot.

Chris - In the population at large, a person picked at random, how likely are they to have a very profound peanut allergy and are you seeing that number climbing, staying the same, decreasing?

Pam - Well, 2 percent of children have a peanut allergy so that means one in every fifty. You could say almost nearly one in every primary school class.

Chris - And has that changed?

Pam - It was very rare to have a peanut allergy until the 1990s. We hardly ever saw a case and there was a big increase in the 90s. It’s gone up, yes, it’s gone up three or four more times since then. We haven’t actually got the latest data so we feel it’s probably leveling off but, without hard data to show that.

Chris - When a person has a very profound reaction what’s actually happening to their body so that they have that collapse and anaphylaxis?

Pam - They’re having this very widespread histamine release which cause a whole range of different symptoms. But particularly in these severe reactions with peanuts the main problem is very bad breathing, so they either get really severe asthma. Even more often closing up of the lining of the throat so they are basically being asphyxiated.

Chirs - How do you investigate them?

Pam - We just put a little bit of peanut solution (an extract of peanut) onto the skin and prick it into the skin. It’s not like a blood test, it’s a very minor thing to do. And you get swelling and redness and itching, so you get a think that looks a bit like a nettle sting.

Chris - And that tells you this person is reacting, so you know they’ve got an underlying allergy? How do you then manage them?

Pam - The current management is avoiding the food, so avoiding peanut. Now that’s tricky because peanut is hugely widely used in the food industry so it’s in loads of things. Not just the things you might expect but it’s added to unusual things so it’s very hard to do that. That’s the mainstay of treatment combined with carrying the medicines to treat reactions, and the particular one for the very severe reactions is an adrenaline pen.

Chris - The treatment that you’ve been investigating is rather than treat the symptoms and rescue people, you’re trying to stop it happening at all?

Pam - Yes. We’ve been trying something called desensitisation. What that involves is trying to reprogramme the immune response, switch off the harmful allergic response and instead induce a beneficial response. It’s not usually possible to do it totally but you can certainly downregulate the bad response and upregulate, increase the good response.

Chris - How do you do it?

Pam - We start with very small amounts of peanut and it’s given by mouth, taken every day. And every two weeks the patient comes back to our clinic, we increase the amount they’re given and then they take that same dose at home, so every time they have a bigger dose they’re in a safe environment with doctors and nurses. It takes 14 weeks to go from a very tiny dose up to taking between 1½ and 2 peanuts equivalent. It’s not given as peanuts but it’s given as a measured protein, peanut protein.

Chris - We’ll hear how Dillon got on…

Maaike - There’s quite a lot of peanut flour in there.

Katie  - Maaike, you’ve got what looks like a chocolate mousse pot…

Maaike - And we open the capsule carefully over the mousse and then we mix it in. Good job.

Dillon - Yes! 

Maaike - It’s given us the freedom to engage in usual family life, and go on holidays, and in the event that Dillon is accidently exposed to peanuts somehow, he will will be able to tolerate that much better than he could before.

Chris - So you heard there they’re sprinkling little bits of peanut extract onto something he likes eating to make sure he continuously presents the particular thing he’s allergic to. But why does that work Pam? Why does that downregulate the profound response he was having before?

Pam - It is changing the regulatory cells that are in the system which control the production of this allergic or harmful antibody so it’s trying to reduce the production of that. And we can show that by monitoring these patients with these tests that the allergic antibody gradually declines.

Chris - What stage are you at with this though? Because we heard from Dillon, he’s one of your patients. Is this something that people can routinely come and seek out from you clinic yet?

Pam - No. Well, we’ve done a lot of research, which has been published, which clearly shows the treatment is effective. What we’re doing now is offering a sort of early access to treatment. We haven’t got a licensed medicine. So we’re well on the way to that and we’re coming up to the last step in the pathway. We’re doing that but, in the meantime, we’re offering this early access to treatment. We’re doing it in the Cambridge Peanut Allergy Clinic where we offer this treatment as part of a range of services we offer. Unfortunately, we’re only able to do this privately because the NHS have not yet commissioned this and are unlikely to do so until we’ve got a full license. So it’s restricted, but it works on most people. We have currently in our clinic we’re having success in high 90s - 95 percent plus patients we can achieve this, so pretty impressive.

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