NEW YORK (Reuters Health) - Vaccination with genetically engineered birch allergens prevent progression of disease in patients allergic to birch pollen, with fewer side effects than conventional immunotherapy, according to a report in the August 9th Early Edition of the Proceedings of the National Academy of Sciences.
“Immunotherapy, i.e., therapeutic vaccination of already allergic patients, is limited by several factors in its application,” Dr. Rudolf Valenta from University of Vienna, Austria told Reuters Health. “Hence only a relatively small percentage of the allergic population (25% of the world’s population is allergic with constantly increasing prevalence) is treated by immunotherapy.”
Dr. Valenta and colleagues developed an allergen-specific immunotherapy based on genetically engineered allergens with reduced allergenic activity and tested it in 124 birch pollen-allergic patients.
Vaccination with recombinant birch pollen allergen derivatives induced strong rises of birch-specific IgG, the authors report, in a response toward the Th1 phenotype. This contrasts with the usual Th2-like immune response induced by immunotherapy with natural allergen extracts.
Vaccination also induced subtle increases in allergen-specific IgA and IgM, the report indicates.
Sera from vaccinated patients inhibited birch allergen-induced histamine release by basophils from pollen-allergic individuals about 10-fold, the researchers note, and symptom improvement in birch-allergic patients correlated with increases in IgG1 antibodies after vaccination.
Vaccination also mitigated the seasonally induced rise in IgE responses after the birch pollen season as late as 1 year after a single course of treatment.
Moreover, 7 of 25 patients with allergies to birch-cross-reactive food allergens experienced improvements in their oral allergy syndrome, the investigators report.
“With the new technology (genetically engineered allergens) we hope to open a new field of prophylactic vaccination,” Dr. Valenta said. “My vision is to formulate prophylactic vaccines against the most common allergies. I believe that this is feasible, because most of the common allergens are cloned.”
He thinks his group’s proof-of-principle obtained with birch pollen allergy “can be generally applied.”
Dr. Valenta added, “We are currently using the same principle (i.e., recombinant technology) to engineer therapeutic vaccines for grass pollen, mite, animal dander, and insect venom allergies. At present three clinical studies are running, two in the birch pollen and one in the grass pollen allergy area.”
Source: Proc Natl Acad Sci USA 2004.doi:10.1073/pnas.0404735101. [ Google search on this article ]
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