Scientists have devised a new, experimental approach to treating allergic diseases that is showing promise in animal studies and could be a potential treatment for humans.

Researchers at the University of California at Los Angeles (UCLA) and the University of New Mexico designed a genetically engineered molecule called GE2 that interacts with two types of immune system cells playing key roles in allergic reactions - basophils and mast cells. In people with allergies, these cells respond to ordinarily harmless substances, such as pollen or peanut proteins, by releasing chemicals such as histamine that trigger the symptoms of allergic reactions. Histamine causes swelling, sneezing, itching, and irritation. GE2 binds to receptor molecules on mast cells and basophils that control the release of histamine that significantly slows or stops the allergic reaction. In tests on mice, GE2 significantly reduced allergic skin reactions.

The GE2 molecule is called a fusion protein because its two active parts are connected, or fused, by a linking section. It contains active sites that indiscriminately bind to and block to any allergen. The scientists used this genetically engineered molecule to connect two receptors on the key immune system cells that cause allergic reactions. Cross-linking these receptor molecules short-circuited the type of allergic reaction that leads to various allergic diseases.

In laboratory tests on human mast cells and basophils, higher doses of GE2 lead to lesser release of histamine. Although many more laboratory and animal studies will be necessary before this approach can be tested in humans, it has the potential to treat such diseases as allergic asthma, allergic rhinitis, chronic urticaria (hives), and even the serious anaphylactic reaction.

Nature Genetics May 2002, Vol. 31(1)