Hope for Allergy Victims

More than 35 million Americans suffer from allergies--the irritating and sometimes incapacitating ailments caused by overreaction of the body's immune system to substances like ragweed pollen, mold spores or a wide variety of foods. Doctors have for decades sought better ways to alleviate allergy symptoms, which include sneezing, shedding tears, itching and swelling. Now, after three years of work, Dr. Robert Hamburger, 52, of the University of California at San Diego, has synthesized a small molecule that interferes with the immune mechanism and helps prevent the discomforts of the allergic.

Hamburger based his work on earlier discoveries of how the immune system causes allergic reactions. Researchers had determined that Immunoglobulin E (IgE), a blood fraction involved in fighting off invasions by foreign substances, is often present in abnormally large amounts in allergy victims. The Y-shaped molecules join with allergens such as pollens and then lock onto special sites on the surfaces of the connective tissue structures known as mast cells, causing them to release histamines, which in turn trigger allergy symptoms.

For years, experimenters have been analyzing the complex IgE molecule in an attempt to find the precise part of its chainlike structure that--like a key fitting into a lock--binds the whole molecule to the mast cell. Experimenting with one segment of the chain, Hamburger finally found and analyzed the structure of the binding part. He then synthesized it, producing a pentapeptide, or chain of five amino acids, that is capable of fitting the binding site on the mast cells. Injected into an allergy victim, the pentapeptide occupies the binding sites on the mast cell and blocks the complete IgE molecule from attaching itself and causing an allergic reaction. Hamburger, who himself suffers from hay fever, then tested the effectiveness of his blocking agent by experimenting on himself, his wife and two daughters and a colleague, Dr. W. Virgil Brown, whom he describes as "exquisitely allergic to guinea pigs." Injecting some of Brown's blood serum under his own skin, Hamburger found that he developed a classic allergic reaction, complete with large red welts, when he exposed himself to guinea pig extract. But after he injected himself with the peptide, his allergic reactions were reduced by 80% to 90%.

The success of Hamburger's preliminary experiments does not mean that a drug to prevent allergic reactions will soon be available. Extensive testing remains to be done. Hamburger estimates it will take at least six years.

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