- The Washington Times - Sunday, April 30, 2000

It happens every spring. Ragweed and pollen make an appearance along with tissues, watery eyes and allergy medications. Some allergy medicines work, but others can be practically useless for some sufferers.

Researchers at Johns Hopkins University and the University of California at San Diego say they believe they are on the way to developing an allergy vaccine that will work better and faster.

The new vaccine involves attaching a small bit of synthetic DNA to allergens that are reintroduced to the body to create an immune response.

"Our first experience of testing this new vaccine approach in ragweed-allergic people supports the hypothesis that this might be a safer and potentially more effective vaccine for allergies," says Dr. Peter Creticos, associate professor of medicine at Hopkins.

People suffer allergic reactions when their immune systems overreact to an allergen such as ragweed. The allergen typically induces certain immune cells, including the type 2 helper T cells (Th2), to produce a variety of chemicals responsible for allergy sufferers' symptoms, such as itchy eyes, sneezing, skin rash and scratchy throat.

Traditionally, doctors have injected a sufferer with a vaccine containing the allergen that is causing the trouble. The body then produces less Th2 than it would if the person were to encounter the allergen naturally, and the vaccine causes the body to produce allergen-attacking antibodies.

After a series of vaccinations, the immune system becomes a better fighter when the actual agent attacks, says Dr. Marshall Plaut, chief of the allergic mechanisms section at the National Institute for Allergy and Infectious Disease.

However, some vaccines are ineffective because the antigens that are injected cause the person to suffer the exact symptoms he or she is trying to avoid, Dr. Plaut says.

The Johns Hopkins and UCSD researchers discovered that they could "mask" the allergic sites on the allergen molecule by attaching a specific short sequence of synthetic DNA to the allergen. The research showed that this DNA sequence can induce the body to produce protective molecules, the type 1 helper T cells (Th1). The Th1 cells inhibit the Th2 cells responsible for the allergic symptoms.

"In animal studies and in lab tests with human cells, this approach has been shown effective in terms of being able to generate immunity," says Dr. Lawrence Lichtenstein, Johns Hopkins professor of clinical immunology.

In the second part of the study, the vaccine was tested on humans. Six ragweed-allergic volunteers underwent skin testing to determine allergic response with ragweed and then with the new vaccine.

The researchers found the new vaccine to be 180 times less allergenic than the ragweed. The researchers hope to test it in a clinical trial soon.

"This new technique could be very potent," Dr. Plaut says. "It looks to be extremely effective at blocking allergic responses. Traditionally, the responses are not blocked but make other responses and have a weak effect on [immune] response."

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