A molecule designed to block cat allergies successfully prevented allergic reactions in laboratory mice, as well as in human cells in a test tube, University of California, Los Angeles (UCLA) researchers report in the April issue of Nature Medicine, available online now. In the future, the investigators say, these promising results could lead to a new therapy not only for human cat allergies, but also possibly for severe food allergies such as those to peanuts. The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, funded the research. “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,” says NIAID Director Anthony S. Fauci, M.D. The injectable treatment puts a brake on the release of a key chemical from cells involved in cat allergy reactions. That chemical, histamine, brings on allergy symptoms such as sneezing, wheezing, itching, watery eyes and sometimes asthma. When a cat-allergic person touches or inhales a protein found in cat saliva or dander (small scales from skin or hair), key immune system cells respond by spewing out histamine. Allergy experts estimate that 14 percent of children 6 to 19 years old are allergic to cats. The treatment comprises a molecule that loosely tethers a feline and a human protein together. The feline end is the notorious protein (called Fel d1) found in cat dander and saliva that causes so much misery in allergy sufferers. On the other end sits a piece of human antibody (called IgG Fcƒ×1) that docks to a cell receptor that can be recruited to stop allergic reactions. The investigators named the chimeric molecule GFD, or gamma Feline domesticus, for its human and feline parts, explains principal investigator Andrew Saxon, M.D., of UCLA. The cat allergen end of GFD binds to antibodies on the surface of the cell. The human end of GFD links to a different cell surface protein (called Fcƒ×RIIB) that interrupts the allergic response.
