Scientists at ImmuLogic Pharmaceutical Corp. and theircolleagues at the University of Virginia, Charlottesville, havecloned the protein that prompts sneezing and itchy eyes in thepresence of house cats.
Janet Bush, vice president, told BioWorld that the Cambridge,Mass., company expects to start Phase I tests of allergytherapy based on the cat allergen by the first quarter of nextyear. "This product is the first in what we plan as a family ofproducts to treat specific allergies," including those toragweed, dust mites and grasses, Bush said.
About 10 percent of the U.S. population is allergic to cats.
The researchers, reporting in the current issue of theProceedings of the National Academy of Sciences, defined theamino acid sequence of Fel dI, found in the saliva, sebaceousglands and pelts of cats. "Airborne levels of Fel dI found inhouses with cats are often in excess of those required toprovoke an asthmatic response," the researchers said.
Sequencing Fel dI revealed that the allergen has certainsimilarities with a uterine protein, uteroglobin, that appearsto protect the lining of the womb, for instance, by limiting theimmune response of the mother against the embryo duringimplantation.
"Since Fel dI has no known biologic function," the scientistssaid, "it is interesting to speculate why cat skin epithelia isubiquitously coated with the protein." Perhaps the proteinserves an immunomodulatory, protective function in the skin,they added.
The primary structure of Fel dI should help clarify the humanimmune response to the allergen and contribute to "moreeffective disease management for cat-allergic patients," theresearchers concluded.
The company's strategy is to use fragments of allergens tostimulate T cells, in contrast to conventional desensitizingallergy therapy that uses a whole extract and involves moremembers of the immune system.
Using fragments is safer, Bush said, since it avoidsstimulating mast cells to release histamine, and thereforedoes not risk anaphylaxis, the hypersensitivity that can resultin life-threatening respiratory distress and shock. Therapyproceeds more quickly as larger amounts of allergen fragmentscan be injected compared with the minute amounts ofallergenic whole extracts that must be used in conventionaltherapy to avoid anaphylactic reactions.
The stock (NASDAQ:IMUL) closed at $18.75, up 25 cents, onTuesday.
-- Roberta Friedman, Ph.D. Special to BioWorld
(c) 1997 American Health Consultants. All rights reserved.