Science has been coming through for peanut allergy sufferers lately. In February alone, researchers announced that yogurt could be a possible cure, a skin patch may be a new treatment and giving kids peanuts during their infant years could help avoid the allergy altogether. Cures for peanut and other food allergies are so sought after because exposure can happen unknowingly and the body’s response can be traumatic, sometimes fatal. How, then, does such a reaction occur?
Food allergies happen because the immune system misidentifies harmless proteins as invaders and puts the body on the defensive. The physiological response to allergens involves three players in the immune system: B cells, immunoglobulin E (IgE) and mast cells.
B cells patrol the body for foreign proteins. When a B cell of an allergy-prone person comes across an allergen for the first time, it secretes a large quantity of molecules called IgE that are custom-made for that particular allergen. The IgE molecules attach to mast cells, which are found all over the body but especially in the nose, throat, lungs, skin and gastrointestinal tract, preparing the body to respond to the allergen when it returns. The first encounter with an allergen does not induce a strong allergic reaction, however.
The next time the allergen enters the body, it catches onto the IgE molecule tethered to the mast cell and triggers the mast cell to release chemicals that cause the itching, sneezing, runny nose and other allergy symptoms. The symptoms localize to where the allergen enters, but if the mast cells release enough chemicals that end up in the bloodstream, the response spreads all over the body. This can cause an extreme drop in blood pressure and closing of the airways, also known as anaphylactic shock.
The IgE-mast cell system is meant to protect the body from parasites. Scientists are still trying to understand why it reacts to harmless substances and, more importantly, how to stop these reactions. With the findings reported recently, perhaps a solution is within reach.
Maggie Kuo, PhD, is the former Communications and Social Media Coordinator for APS. Catch more of her writing in the Careers Section of Science Magazine.