Allergic disease – the umbrella term that covers food allergy, eczema, asthma and allergic rhinitis – is understood more now than in the past. As we have previously discussed, what happens in the body during an allergic reaction is also better recognised – at least for immediate, IgE mediated reactions. Why it happens, and how exactly to prevent it or cure it is, unfortunately, less well understood. However, research is taking place all the time and the study of allergies is receiving much attention because of the huge increase in the number of sufferers that have been seen over the past decades.
This focus on research into allergies has meant that new strategies to change how the body responds during an allergic reaction and new methods of treatment are being trialled. There are now promising forms of treatment, called immunotherapy, which are in their infancy but could possibly be the future of allergy treatment. This chapter will briefly discuss these developments and touch on the current research within the field of allergy in order to show the bigger picture of managing your child’s symptoms. Chapter 7 discusses some everyday ways to manage your child’s allergies.
The central pillar of food allergy management is avoidance of the offending allergen. In the case of milk allergy, especially as it is often the main source of nutrition in the child, avoidance affects everything. The involvement of a paediatric dietician is key. Education on how to read food labels and avoid milk as well as choosing an appropriate substitute that ensures complete nutrition requires considerable expertise. Further education on how to recognise and treat the reactions that may result from accidental exposure is also important. Regular follow-up to monitor growth and the possible development of tolerance is also needed, as is a holistic approach to ensure the early recognition and treatment of the other emerging allergic conditions that your child may have.
As I was breastfeeding S, they suggested that I came off dairy for a week and see what happened to his symptoms. Within two days he turned into a very content, smiley little baby who rarely cried, the difference was astonishing.
HANNAH, MUM OF S
I took milk out of my diet and the eczema significantly improved. This was sometime around Christmas 2009 – nine months since it first appeared, and so months of agony for the poor boys, very little sleep for any of us and a broken mummy.
EMMA, MUM OF CAMERON AND DILLON
Food elimination is a challenge of its own but has huge rewards for your child and little detriment, if carried out carefully and managed well.
Recent research has established that up to 70 per cent of children with IgE mediated milk and egg allergy are able to tolerate baked milk or egg in their diet. This can make life much easier. Such children tend to have a milder type of milk or egg allergy associated with milder reactions, smaller allergy tests and early outgrowing. New studies suggest that introducing baked egg or milk to the diet when it can be tolerated may also speed up the process of outgrowing the whole milk or egg allergy. However, testing to differentiate children who are and are not tolerant to baked milk or egg is limited and children can have severe reactions. This means that supervised challenge testing, best directed by a specialist doctor, is required. You should discuss this with your doctor if you think it may be relevant.
Immunotherapy works by modifying the way that the body reacts to an allergenic substance, in order to desensitise the allergy sufferer. The term ‘desensitise’ means that the immune system is less sensitive and less likely to react to the allergen and that only greater levels of exposure will cause a reaction. Unfortunately, this type of approach has only proved useful for IgE but not non-IgE mediated reactions. If you remember back to Chapter 1, we looked at how the body reacts incorrectly to food because the immune system wrongly recognises harmless food proteins such as egg protein, identifying them as harmful. This causes the immune system to react, resulting in an allergic response with the itching, swelling and other symptoms that you see in your child.
By changing the body’s immune system, scientists believe that they can change the way that the body reacts to a harmless food protein and therefore change the immune response and ultimately reduce any allergic response. This is the principle behind desensitisation. It is now recognised as a highly specific and effective method to treat certain types of allergy. The concept is not new. Immunotherapy has been in use for over a hundred years in the treatment of allergic rhinitis to grass pollen. It is also well established in the management of bee and wasp venom allergy.
To desensitise the allergic rhinitis sufferer, drops or tablets of the pollen allergen are placed under the tongue of the sufferer in increasing doses. This can also be done with injections. As a result, the allergic rhinitis sufferer becomes desensitised to pollen over time, with the effect increasing over the course of a three-year period of desensitisation. Occasionally, this can lead to an almost complete resolution in symptoms but more often it simply reduces them to more manageable levels. After a three-year period of treatment the effect usually persists even though the treatment has been stopped. Desensitisation with pollen has also been shown, within this group of allergic rhinitis sufferers, to reduce the risk of progression of allergic disease from allergic rhinitis to asthma, which is something that is otherwise very common. While the mechanism by which desensitisation works remains unclear, it is starting to unravel. The clear success of desensitisation in allergic rhinitis sufferers has led to researchers and clinicians who specialise in allergy to look at similar methods of treatment for other allergies, including food allergy.
Desensitisation with food allergy involves the administration of the food allergen to the patient in small but increasing doses. Most trials give the child a very small amount of the allergen to eat or drink with close observation and then keep the tolerated level in the diet at home on a regular basis. The aim is to raise the level of allergen your child can ingest and cope with, without having a reaction. Once this is achieved, a maintenance dose is continued to uphold this desensitisation.
Unfortunately, there have been two troubling issues with this treatment. The first is the sometimes severe side-effects, which have led to attempts at injection desensitisation to food being abandoned. There are also issues with desensitization by placing the allergen in the mouth, which can cause occasional but severe reactions. Another issue is the lack of long-lasting effects seen once consumption of the allergen is stopped in many children. Desensitisation with food seems to have a temporary effect, lasting only for the duration of active treatment. In other words, the child does not develop tolerance (the ability to ingest the allergen without symptoms despite periods of allergen avoidance). After a period of avoiding the allergenic food, your child will react again to the allergenic food when it is ingested. Is it worth the effort and risk of ingesting regular doses when the end result is still not being rid of the allergy? Desensitisation for food allergy is also not in everyday use in the clinical setting as yet but remains the subject of intense study.
Ongoing research into the prevention of anaphylaxis and food allergy in general is vital. New and novel therapeutic approaches with the aim of reducing reaction, encouraging tolerance or curing food allergy are emerging as knowledge is advancing. Immunotherapy is taking an increasingly important role. Remarkable progress has been made within the field of food allergy treatment. As these strategies progress beyond the research stage, disease-modifying therapies rather than food avoidance may become the standard of care, and the increasing incidence of anaphylaxis occurring may even be reversed over the next decade.
There are studies that have been carried out and are ongoing which look at immunotherapy for peanut, milk and egg allergies. Further studies are needed, however, and there are risks involved. A number of children drop out of the studies because of allergic reactions and gastrointestinal symptoms. The studies are looking at the use of different ways to administer the food allergen, as well as measuring the effect that it is having on the child. The methods being used are oral immunotherapy, where the allergen is ingested, which we have discussed. There is also sublingual immunotherapy, which involves placing a few drops of the allergen under the tongue, as is used with the pollen allergy desensitisation. With food allergy, it has been found to induce desensitisation but not as effectively as oral treatment or ingestion. The third method is called epicutaneous immunotherapy, where the allergen is given via a skin patch. This is being trialled with milk allergy sufferers and there is currently a peanut trial underway. Finally, there is immunotherapy with modified food proteins, which has been shown to reduce side-effects of allergen exposure.
It is still early days for food immunotherapy and much more research is needed. Immunotherapy to induce desensitisation to food is not used routinely in allergy clinics in the NHS. However, results from trials are promising and it is an area that is likely to be in mainstream use in the future, especially for those who are unlikely to become tolerant to a food naturally, such as those with peanut allergy.
There may be a role for anti-IgE therapies in treating food allergy. In Chapter 1 we discussed IgE, the antibody that identifies the harmless food protein and thereby triggers the immune response. IgE also plays a pivotal role in severe and anaphylactic food-related reactions. Therefore, treating the allergy sufferer with an injection therapy to block the actions of IgE is a promising idea.
One study using this method has shown that peanut allergy sufferers treated with anti-IgE therapy react only to a much higher level of peanut protein, meaning that they tolerate greater levels of peanut (see see References, here). Astonishingly, the level that the sufferer can then tolerate may be much higher than the level that caused anaphylaxis through accidental exposure. While these results are encouraging in terms of the prevention of anaphylaxis, the method only works if the sufferer has regular injections, which are very expensive. Research now is therefore looking at combining anti-IgE therapy with desensitisation (here). It is hoped that this combination may reduce the amount of side-effects and nasty reactions that the sufferer experiences while going through the process of desensitisation, but that once desensitised the regular injections can be stopped.
There is other research looking at changing a child’s diet early in life. The aim is to promote the development of tolerance as a way of avoiding allergy developing in children who may be prone to it. One promising example is the LEAP study (www.leapstudy.co.uk), which has taken children aged 4–10 months who have eczema and/or egg allergy. These children carry a 20 per cent risk of developing peanut allergy. The children were randomly split into two groups, one given peanut protein as a weaning food and one told to avoid it. The study is ongoing, but results when the children are five will be compared. It is hoped that the children in the group that have been exposed early to peanut protein will have less incidences of peanut allergy.
Another exciting line of investigation in the treatment of food allergy is the use of Chinese herbs. Animal trials have found that treatment of food allergies with Chinese herbs is safe, straightforward and well tolerated. However, while animal trials have shown good results, human trials are in their early stages. Again, much more research is needed before this could be a successful way to treat food allergy.