ALLERGY VACCINE MAY HAVE CAT LOVERS PURRING.

Byline: L.A. McKeown Medical Tribune News Service

Cat lovers who become sneezy, itchy and teary-eyed when they get too close to their favorite feline soon may get help from a new vaccine that eliminates some of the uncomfortable symptoms of cat allergy.

Maryland researchers report success with a new vaccine that reduces symptoms faster and requires fewer injections than standard allergy shots.

Traditional allergy shots, also known as immunotherapy, consist of mostly water and extracts of cat dander - the dead skin cells that trigger reactions in allergic people.

Like pollen, cat dander is an allergen, and allergy shots are based on the theory that giving people small doses of allergens strengthens their immune-system tolerance and keeps the allergies at bay.

Current treatment for severe cat allergy involves an initial series of about 25 shots followed by booster shots every two weeks for months or even years to build immunity.

The new cat vaccine improves on traditional shots because specific allergen parts - called epitopes - have been isolated from the allergen protein in cat dander to maximize the immune system's allergy-fighting capability, the researchers reported in the December issue of the American Journal of Respiratory and Critical Care Medicine.

The vaccine, known as Allervax cat, requires fewer shots during a much shorter period than standard allergy treatment.

In the study of 95 cat-allergy sufferers, only four doses of Allervax were required to reduce symptoms.

Patients were divided into groups and given one of three different doses of the vaccine or placebo every week for four weeks.

Before beginning treatment and again at one and six weeks after stopping treatment, patients were required to stay in a ``cat room'' with two cats for at least one hour.

Before treatment, fewer than half of the people in the placebo group and the highest-dose Allervax group could stay in the cat room for the full hour.

But six weeks after treatment, 15 of 27 people who received the high-dose vaccine stayed in the room without significant symptoms, compared with only 10 of 25 people in the placebo group, reported Dr. Philip Norman of Johns Hopkins University School of Medicine in Baltimore. Although the vaccine was tested at two other doses, the highest dose was most effective.

Other studies are under way to determine if the high dose used in this study will be the one that ultimately will be used if the vaccine is approved for use. The vaccine will not be available commercially until at least 1998, according to the researchers.

The scheduling of the shots also is being modified to determine how best to administer the vaccine, said Dr. Harold S. Nelson, a Denver researcher who participated in a larger trial of the vaccine that occurred after this 95-person study. He said the results of that trial will be presented in February at a meeting of the American Academy of Allergy, Asthma and Immunology in San Francisco.

Another issue that still has to be resolved is whether the four shots will keep cat lovers symptom-free indefinitely.

``There is no data right now on the duration of the effect,'' Nelson said. ``So, we don't know if a booster will be required in these people at some point.''