Vaccine zaps allergy in record time

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ALLERGY sufferers could bid farewell to their sneezes with a new generation of vaccines that take effect within weeks.

Existing vaccines for allergies involve three to five years of regular injections with increasing amounts of allergen - the substance that triggers an allergy. All the while the immune response slowly changes from a predominance of T-helper 2 (TH2) cells, immune cells responsible for triggering allergic reactions, to T-helper 1 (TH1) cells, which stimulate the production of protective antibodies.

Because nothing is directing allergens to the right place in immune cells, it takes a lot of allergen to generate a response.

Now researchers at the Swiss Institute of Allergy and Asthma Research (SIAF) in Davos Platz have developed "modular antigen translocating molecules" (MAT), which make vaccines more efficient by delivering the antigens - foreign substances that trigger an immune response - right to where they're needed within an immune cell.

The MAT vaccines trigger the same protective response as conventional vaccines but in a fraction of the time and with much less allergen, according to a study in human cells. "They lower the dose needed to induce a T-cell response by a factor of about 100," says Reto Crameri of SAIF, lead author of the study.

The molecules have three parts: a translocation unit, a targeting unit and an allergen. The translocation unit gets the allergen into antigen-presenting cells that are responsible for engineering the switch to TH1 cells. The targeting unit then chauffeurs the antigens to the part of the cell that packages them up for presentation to TH1 cells, ensuring more TH1 cells meet the antigen and respond to it.

Crameri's team has so far developed vaccines for dust mites, pollen, cat hair and bee venom and tested them on cells from susceptible humans. In each case the vaccines produced a stronger immune response than injecting the allergen by itself (Allergy, DOI: 10.1111/j.1398-9995.2006.01292.x). Crameri says his group is getting similar results with mice injected with these vaccines, and clinical trials on a MAT vaccine for cat allergy will begin later this year. The trial will involve three shots over a four-week period.

The approach is one of several new strategies for tackling allergies. Another vaccine, developed by Allergy Therapeutics of West Sussex, UK, entered phase III clinical trials last week. It stimulates a stronger response by tricking the immune system into thinking it is being attacked by a bacterium. "In the past few years we have really begun to understand the cell signalling mechanisms involved in the allergic response," says Katherine Gundling of the Allergy Immunology Clinic at the University of California, San Francisco. "Now we're asking, 'Can we find a way to take advantage of those mechanisms?'"

source - New Scientist