The humble peanut butter and jelly sandwich, once a common lunchbox favourite, now features on the ban list in many Canadian schools. The seemingly innocuous peanut has potentially lethal consequences for the 2 out of every 100 Canadian children who suffer from allergies (1). Peanuts are at the top of the most reaction-causing foods, among tree nuts, cow’s milk, eggs, soy and wheat (2). Alarmingly, peanut allergies present very early in life, are less likely to resolve in adulthood, and can cause deadly anaphylactic shock with even trace amounts of exposure (3). To tackle this problem, the molecular processes involved in allergic reactions are the subjects of intense research for many Canadian scientists and clinicians.
If you are among the 2.5 million Canadians living with a food allergy (1), exposure to an allergen triggers your immune system to overreact, producing large amounts of an antibody called Immunoglobulin E (IgE). These antibodies recognize specific target allergens, from pollen to pet hair. IgE molecules attach themselves to immune mast cell receptors, thus acting as a ‘primer’. Following this, even minute quantities of the offending allergen provokes the release of a huge amount of inflammatory chemicals from mast cells, such as histamines and cytokines, which are responsible for the symptoms of allergies (3).
Specific proteins associated with peanuts have been identified as the causative factors in activating these immune responses. Of these 13 known allergenic proteins, Ara h1 and 2 have particularly strong binding affinities to IgE, and adversely affect the majority of peanut-sensitive patients (4). Interestingly, these proteins belong to the vicilin and conglutin families of seed storage proteins, which are found abundantly in many commonly consumed legumes. This may account for the cross-sensitivity to peas, soybeans and tree nuts by many peanut allergy sufferers. This also makes the main therapeutic strategy, complete avoidance, challenging for those with especially severe reactions. In the case of accidental ingestion, mild symptoms such as itching and a runny nose can be treated with antihistamines. However, immediate administration with an adrenaline shot is required for more extreme, life-threatening symptoms like throat swelling.
The Canadian Allergy, Genes and Environment Network (AllerGen NCE) was established in 2004 to mobilize researchers and healthcare providers towards improving the quality of treatment and care for those suffering from allergies. Over 170 scientific investigators across 47 disciplines form AllerGen’s diverse member base, with the goal of driving innovation in allergy therapies. Among them is UBC’s Professor Kelly McNagny, AllerGen’s Associate Scientific Director, who studies the molecular basis of inflammatory responses involved in allergic conditions such as asthma. In addition, his research team is also interested in identifying components in the blood that can be used to predict an individual’s likelihood of developing an allergic disease.
Another AllerGen affiliate, Dr. Edmond Chan, is the head of the Allergy Clinic at BC Children’s Hospital. Dr. Chan is a strong advocate for revised policies aimed at nipping childhood allergies in the bud. Paediatricians and parents have been proponents of a North American guideline set in the early 2000s to avoid peanut exposure in children until after they turn 3 years old. However, emerging research from the UK and Israel shows that feeding infants peanuts during their transition to solid foods, at around four months of age, actually lowers their risk of nut allergies by up to ten times. Dr. Chan is the only Canadian member of the U.S. National Institutes of Health’s expert panel on childhood allergies and is pushing for new tactics in allergy avoidance to be shared with the community.
Accumulating evidence is painting a better picture of the physiology driving the onset of food allergies. Evolving healthcare protocols to diagnose and treat allergies as well as changing how we grow, process and consume foods will be integral in supporting the 3500 Canadians that suffer from anaphylactic shock annually (5).
Curious about more of the science behind allergic reactions? Cafe Scientifique Vancouver is hosting a free event showcasing the latest research in the field of food allergies from an expert panel, including Dr. Edmond Chan and colleagues from BC Children’s Hospital. All are welcome at this informal discussion on June 27, 7:30pm at the Fairview Vancouver Pub.
(1) Food Allergy Canada (2015) Fast Facts: Food Allergies in Canada.
(2) American College of Allergy, Asthma & Immunology (2014) Food Allergy.
(3) Gould and Sutton (2008), IgE in allergy and asthma today, Nature Reviews Immunology 8, 205-217
(4) Mueller, et al. (2014), The Molecular Basis of Peanut Allergy, Curr Allergy Asthma Rep. 14(5): 429.
(5) Canadian Anaphylaxis Initiative (2017) Raising Awareness for Anaphylaxis.
Tara Fernandez is a science communicator and Cell Biologist at UBC. Her research focuses on the molecular causes of obesity and diabetes. She also enjoys getting people excited about science, and is a facilitator for Cafe Scientifique Vancouver.
