Peanut allergies - can they be reversed?

22 May 2018

Interview with 

Dr Pamela Ewan, Cambridge Peanut Allergy Clinic

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Allergies can vary widely in severity. While some are undoubtedly inconvenient, others can actually be life threatening. Chris Smith spoke to Pamela Ewan from the Cambridge Peanut Allergy Clinic. But first, Katie Haylor heard about what it's like to have a peanut allergy. She spoke to Maaike and her son, Dillon...

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 his arm was in a sack of peanuts and he came back into the house and rubbed his eyes 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 because you need to keep them safe. We’ve been unable to be spontaneous. It makes your world very small to begin with but, luckily, we have the resources and the kind friends and family to make it possible to do lots of normal things.

Katie - It sounds like it’s something that takes a lot of planning, a lot of effort and is quite stressful?

Maaike - Yeah, I think that’s accurate. It’s huge in its detrimental effect on family life.

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 would a parent first notice that their child is like Dillon? 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 - And Pam, is there an age at which you grow out of allergies? Or can you grow into them paradoxically as you get older because this is something I’ve often wondered because I think I have less bad hay fever in my adulthood than I did in my childhood, or is that just because I’m better at avoiding the problem?

Pam - Mostly people develop an allergy either in childhood or early adult life but we see a few people, even into their 70s getting their first allergy. On the whole, most adults have got allergy don’t actually get better, but certainly some do and particularly described for hay fever waning as they get a bit older. We don’t really fully understand this but I think it’s a balance between the drive to allergic antibody versus those forces we talked about earlier which are trying to switch that off or downregulate it.

Chris - Something that Sheena said was mothers not eating peanuts when they were pregnant. There was some countries where this was put out as advice, wasn’t it, and then they did see an apparent increase in peanut allergy afterwards? Where do you stand on that?

Pam - That advice as actually not scientifically based. So it was thought to be a good idea but there was no solid evidence to support it. There is a study now which tried a very early introduction of peanut into babies and they did manage to lower the incidence of peanut allergy. But a problem they encountered in that study was that when they tested quite small children they found they already had a peanut allergic antibody, the bad antibody, so it’s not that simple to do. So it would be risky for mothers to start feeding their children peanuts without actually knowing did they have that allergic antibody on board or not, so it’s not something people should just try randomly.

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 - What is very important is do do what we doctors call’ take a history.’ That means we go into the details of exactly what happened, timing in relation to food, did they know what they’d actually eaten, did they know what the symptoms were. So we form a picture in that way then we back it up with tests.

Chris - When you say that what would you do? You’d expose someone to a bit of peanut?

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 what happens is you get this reaction that Eoin was describing earlier, histamine release 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 - So one would administer that the minute you think you’ve been exposed or that you begin to get symptoms?

Pam - When you get symptoms yes, because you can have a range of severity. It’s not everybody who’s going to have devastating reactions. So these patients will carry antihistamines and the adrenaline pen if needs be.

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 - I should say this is very new for a food. So immunotherapy or desensitisation has been around for a hundred years but it hasn’t been tried for foods until very recently. 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…

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

Maaike - And we open the capsule carefully over the mousse and we put it in. There’s quite a lot of peanut flour in there. Then I check to make sure it’s empty and then we mix it in. Good job. Good boy.

Katie - So now you’ve done that bit it’s time for sweets.

Maaike - It’s given us the freedom to engage in usual family life, and go on holidays, and see friends, and be excited about an ice cream van instead of dreading the sight of one. And it’s also given us increased safety and I mean that’s a fundamental change I think 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 - Basically, it is changing the regulatory cells that are in the system which control the production of theis 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 and we’re working on further research which will actually take a while. It’s quite complex getting a drug licence but we’re well…

Chris - What for peanuts?

Pam - Though it starts as a foodstuff, we have to do it exactly as stringently as you would if you were making a drug out of a molecule. So we have to go through the whole regulatory system which is massive. So we’re well on the way to that and we’re coming up to what is called the phase 3 trial which is 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’s probably better than nothing.

Chris - And just very briefly, does this work on everybody?

Pam - 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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