Cambridge University scientists have identified how allergic reactions to cats are triggered.
Researchers believe that a protein found in cat dander -- microscopic skin particles shed by animals -- can trigger an allergic response in humans when it comes into contact with a common bacteria.
Reactions can include sneezing and coughing, swollen, itchy eyes and breathing difficulties, similar to the symptoms of a common cold.
Scientists are hopeful that the research, published in the Journal of Immunology, could lead to the development of new treatments, not only for cat allergy sufferers but also for people allergic to dogs.
The most common allergen is the Fel d 1 protein, which is found in cats' saliva and spreads easily to their skin when they groom themselves.
An allergic reaction is triggered when the protein comes into contact with a common bacterial toxin, scientists said.
"How cat dander causes such a severe allergic reaction in some people has long been a mystery," said Dr Clare Bryant, lead author of the research from the university?s veterinary medicine department.
Scientists have not only identified the toxin which kickstarts the immune response to cat dander, but also the part of the immune system which recognises it, Bryant said.
An allergic reaction occurs when the immune system overreacts to a perceived danger.
Instead of responding to a harmful virus or bacteria, it misidentifies allergens, such as dander, as dangerous and mounts an immune response.
"We are hopeful that our research will lead to new and improved treatments for cat and possibly dog allergy sufferers," Bryant added.