Specialist cells in the intestine are behind allergic reactions to food, researchers have said, with their findings set to transform food allergy treatment.
Much is already known about how injected allergens, such as insect bites, bring on anaphylaxis, a quick, body-wide allergic reaction which in severe cases can be deadly.
However, less has been known about anaphylaxis in the gut prompted by eating a food allergen.
Thanks to researchers in America, that understanding has taken a big stride forward, after the team highlighted what could be driving anaphylaxis in the gut: specialised immune cells in the intestine that produce strong chemical messengers.
These messengers, which scientists already know play a key role in asthma attacks, prompt muscles in the airways and gut to contract and increase inflammation. The latest findings show they play a key role in severe food allergy reactions that start in the gut.
It demonstrates that anaphylaxis in the gut is markedly different from anaphylaxis that occurs when an allergen enters via the bloodstream directly.
The study authors explained: “Until now, we assumed that anaphylaxis followed the same pathway regardless of where allergens entered the body, with histamine from mast cells as the main driver.
“Our study shows that when allergens are ingested, a specialised set of mast cells in the gut don’t release histamine – instead, they produce lipid-based molecules called leukotrienes. These molecules, rather than histamine, trigger anaphylaxis in the gastrointestinal tract.”
To test their theory, the researchers used the asthma drug zileuton, which works by blocking an important enzyme needed for the production of leukotrienes.
Zileuton alleviated allergy symptoms and stopped the body temperature from dropping to dangerous levels, a key feature of anaphylaxis.
Importantly, these processes were not seen when allergens were injected directly into the bloodstream, demonstrating that the gut pathway differs from the whole-body allergic pathway.
Antihistamines are less effective at treating severe anaphylaxis, particularly those involving food allergies, but the new research shows targeting leukotrienes could provide a new way of treating food-related anaphylaxis.
The study authors said: “Local intestinal responses may be acutely targetable as a therapeutic strategy to prevent anaphylaxis in severely food-allergic individuals.”
Read more in the journal Science