Researchers Learn What Triggers Allergic Reaction to Cats

A new study has identified exactly how cat dander triggers allergic reactions; the find could lead to new treatments for people with cat or dog allergies.

Scientists at the University of Cambridge studying the immune system's extreme reaction to cat allergens learned that the most common source of severe allergic reactions is a protein called Fel d 1, which is found in the particles of cat skin known as dander.

The research team discovered that when Fel d 1 is exposed to low doses of a ubiquitous environmental bacterial toxin known as LPS, it triggers a pathogen receptor (known as TLR4) in the body, which causes a large inflammatory response in the immune system.

Allergic reactions are the result of the immune system overacting to a perceived threat or danger. Cat dander registers like an invasive bacteria or virus and the body responds with sneezing, coughing and wheezing.

With this new knowledge of how cat dander causes allergic reactions, new treatments focusing on eliminating the allergic reaction, rather than the symptoms to the reaction, could be developed.

Clare Bryant, lead author of the research from the University of Cambridge's Department of Veterinary Medicine, is hopeful that the new research will lead to improved treatments for cat and dog allergy sufferers.

"How cat dander causes such a severe allergic reaction in some people has long been a mystery. Not only did we find out that LPS exacerbates the immune response's reaction to cat dander, we identified the part of immune system that recognizes it, the receptor TLR4."

Additional research by Bryan and her colleagues found that the allergen Can f 6 (a protein found in dog dander) also triggers the same immune reaction as the feline dander.

"As drugs have already been developed to inhibit the receptor TLR4, we are hopeful that our research will lead to new and improved treatments for cat and possibly dog allergy sufferers."

Bryant and her colleagues' research is published in The Journal of Immunology.