New compound may prevent allergies

A new chemical compound, partially derived from cats and partially derived from humans, may provide an end to cat allergies, U.S. researchers reported on Sunday. This approach may also work against more dangerous allergies, such as deadly peanut allergies, they add.

The compound, tested in mice bred to be allergic to cats, virtually shut down the histamine reaction that causes the uncomfortable symptoms of cat allergies such as runny eyes, sneezing and itching, Dr. Andrew Saxon of the University of California Los Angeles School of Medicine and colleagues reported.

The compound also worked in human cells grown in lab dishes, the researchers noted in the April issue of Nature Medicine.

"This novel approach to treating cat allergies is encouraging news for millions of cat-allergic Americans. Moreover, these results provide proof-of-concept for using this approach to develop therapies to prevent deadly food allergy reactions as well," said Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases, which sponsored the study.

Allergies are caused when the immune system mistakenly reacts to allergens - such as certain proteins in food, on animals or produced by plants. One response is the production of histamine, which brings on allergy symptoms such as sneezing, wheezing, itching, watery eyes and sometimes Asthma.

The compound stops this process. It uses pieces of an allergy-provoking protein found in cat saliva or dander called Fel d1, tied to a piece of human antibody called IgG Fcg1. The UCLA team named it GFD, or gamma Feline domesticus.

The cat allergen part attaches to antibodies on the surface of the immune system cells that produce histamine, while the human bit stops the cell from getting started.

"We measured more than 90-percent less histamine in the (human cell) cultures with GFD," Saxon said. "Those results suggested that GFD successfully prevented the immune cells from reacting to cat allergen. The next step was to test GFD in mice that we had made allergic to the allergenic protein found in cat saliva and dander."

The researchers tested GFD in two types of allergic mice, and it blocked the excessive immune response in both.

The approach could be used to protect people from a wide array of allergies, the researchers said.