An estimated 10 percent of the U.S. population is allergic to animals, with 20 to 30 percent of asthmatics allergic as well. But a treatment, ridding them of their allergies may be on the way. British scientists have identified the different components that lead to allergic reactions in cats, and along with a drug that's already in clinical trials for other illnesses, they say we're closer than ever to a treatment.

Researchers at the University of Cambridge already knew that when cats lick themselves, "they spread saliva, hormones, and skin cells on their coat." As they shed, dandruff - called dander - falls off with the hair. They found that when it was released in the presence of the common environmental bacterial toxin lipopolysaccharides (LPS), it triggered in humans, an immune response in the protein receptor TLR4, and subsequently, an allergic reaction, CBC News reported.

"How cat dander causes such a severe allergic reaction in some people has long been a mystery," Dr. Claire Bryant, lead author of the study, said. "Not only did we find out that LPS exacerbates the immune response's reaction to cat dander, we identified the part of [the] immune system that recognizes it."

Cat dander is especially hard to avoid. It's considered a "sticky" molecule, and can appear in many places, including people's shoes and clothes, and walls and ceilings, even years after a cat has lived somewhere.

"By understanding the triggering mechanism, there are now drugs that have been designed that are in clinical trials for other conditions, such as sepsis, that could potentially then be used in a different way to treat cat allergy and to prevent cat allergy," Dr. Bryant told BBC News.

While most current drugs available for allergies are antihistamines, the new drug would be more effective for long-term treatment by inhibiting the reaction of the TLR4 receptor and blocking an allergic reaction. Researchers are looking into whether it would be available in pill or inhaler form.

"With just a puff of an inhaler, which contains the drug, a person would be okay to interact with cats without an adverse reaction," Dr. Bryant said.

The charity Allergy UK said the research was a "big step forward" in understanding how cats cause such severe allergic reactions.

"Research uncovering how proteins in cat dander trigger an allergic asthma reaction is an important part of the process of developing new and improved treatments and reducing the risk of asthma attacks," Malayka Rahman, research analyst at Allergy UK, said.

Pet allergies, in general, can cause a range of symptoms, with the mildest symptoms including sneezing, itchiness, watery eyes, and a runny nose. More severe symptoms can include hives, and for asthmatics, difficulty breathing and chest tightness.

"This new information identifying the specific receptor interaction in the immune system could pave the way for treatments for those with persistent disease triggered by cat allergen and, in the future, potentially dog and house dust mite allergen," Maureen Jenkins, director of clinical services at Allergy UK, said.


Herre J, Bryant C, Monie T, et al. Allergens as Immunomodulatory Proteins: The Cat Dander Protein Fel d 1 Enhances TLR Activation by Lipid Ligands. The Journal of Immunology. 2013.