Background: Allergen immunotherapy is the repeated administration of allergen vaccines to allergic individuals in order to provide relief of symptoms and improvement in quality of life during subsequent natural allergen exposure. The aim of this study was to evaluate the efficacy of specific immunotherapy in allergic rhinitis patients sensitized to birch pollen.

Material and methods: 21 allergic rhinitis patients sensitive to birch allergens were divided into two groups: 10 patients received active vaccines, 11 – placebo. Allergen specific immunotherapy was performed using birch allergoid vaccines. Evaluation of efficacy was performed in three consecutive birch pollen seasons with the use of both diaries and questionnaires. Levels of nitric oxide (NO) in the expired air were evaluated using a chemiluminescence analyzer before and during the birch pollen season.

Results: After two years of immunotherapy, patients receiving active vaccines reported less symptoms in their diaries as compared to placebo group. During the second birch pollen season, patients on active vaccination presented with lower exhaled nitric oxide levels as compared to placebo group.

Conclusion: Subcutaneous injection immunotherapy is effective in allergic rhinitis patients sensitized to birch pollen. Specific immunotherapy significantly inhibits allergen induced bronchial inflammation (assessed by exhaled nitric oxide measurements) associated with natural allergen exposure.