Allergy and Immunology

Wheat Allergy - 17/05/2013/1

Non IgE mediated food allergy What is the difference between non IgE mediated food allergy and IgE mediated food allergy? Food allergies may be divided into 2 types – immediate (IgE mediated) and delayed (mixed IgE/non-IgE and non IGE mediated). IgE mediated means that IgE allergy antibodies are a cause of the allergic reaction to a food. This type of reaction is the most common type of food allergy with common symptoms being hives, redness of the skin vomiting and in the more severe reactions anaphylaxis. The IgE antibodies which cause IgE mediated reactions can be identified by skin prick or blood allergy tests. Mixed IgE/Non IgE and Non IgE mediated food allergies are caused by a reaction involving other components of the immune system apart from IgE antibodies

How do the delayed forms of food allergy differ from immediate IgE mediated

food allergy?

Delayed forms of food allergy mainly affect the bowel and the skin and symptoms

develop hours after eating the food. In contrast, immediate IgE mediated food allergy

can affect many systems of the body (skin, gut, airway and circulation) and symptoms

develop rapidly (within 1 hour) of eating the food. The immune mechanisms causing

delayed food allergy are less well understood than IgE-mediated food allergy. The most

common causative foods for delayed food allergies are cow’s milk and soy. Unlike IgE

mediated food allergy delayed food allergies are very rarely life threatening. What are the common symptoms of delayed food allergy? Common symptoms include worsening of eczema, abdominal discomfort, vomiting and diarrhoea. The symptoms often take longer to develop (hours-days) rather than those of IgE mediated food allergies which frequently occur within 5 -30 minutes following food ingestion. How are delayed food allergies diagnosed? Unlike IgE mediated food allergy there are no blood or skin tests which have proved useful in general medical practice. Therefore the diagnoses must be suspected on the history. The diagnosis can be confirmed by showing that the symptoms improve when the suspected food is removed from the diet and return when the food is reintroduced into the diet. This process can take a number of weeks or months to complete properly. Can non IgE mediated and IgE mediated food allergy occur in the same individual? Yes children can have both types of food allergy. This can be the situation particularly in children with severe eczema.

Does my child need an adrenaline injector for delayed food allergy? In general the answer is no as typical reactions are not life threatening. Can children grow out of non IgE mediated food allergy? Yes however there is less information on the time course and proportion of children who grow out of delayed food allergy as compared with IgE mediated food allergy. Are there any allergy tests for delayed food allergy? There are no blood or skin allergy tests which have an established role .The diagnosis is established by removal of the suspected food(s) to see if symptoms improve followed by reintroduction of the food back into the diet to see if symptoms return. Once a diagnosis is established the main step in treatment is avoidance of the relevant food. Your doctor may choose to perform a food challenge test after12 months or so to see if the condition has resolved. What foods can cause delayed food allergies? A range of foods can cause delayed food allergies. Some of the more common foods are cow’s milk wheat and soy. Are there any special types of delayed food allergy to be aware of? Yes there is an entity called FPIES (Food Protein Induced Enterocolitis syndrome). This is an uncommon type of non IgE mediated food allergy. This condition is usually seen in infants and presents with severe vomiting and sometimes diarrhoea. In some babies (up to 10-15%) there can be sudden collapse with pallor. Common triggers are cow’s milk, egg, soy milk and sometimes rice. This condition is frequently misdiagnosed as an acute surgical condition in the abdomen or serious infection. There are often several reactions before the diagnosis is established. Children tend to grow out of this condition more rapidly and many can tolerate the offending food by 18-24 months of age. Another delayed food allergy is a condition called Eosinophilic esophagitis (EOE) This condition appears to be increasing. Symptoms include difficulty swallowing, vomiting and failure to thrive however the condition may be asymptomatic. Common foods include milk, egg, wheat, and soy. Diagnosis involves examination and biopsy of the oesophagus. Treatment includes removal of suspected foods from the child’s diet.