Short-term preseasonal birch pollen allergoid immunotherapy influences symptoms, specific nasal provocation and cytokine levels in nasal secretions, but not peripheral T-cell responses, in patients with allergic rhinitis

Background Birch pollen allergic rhinitis can be sufficiently treated with specific subcutaneous allergoid immunotherapy (IT). However, little is known about the clinical and immunological effects of short-term therapy protocols. Objective To investigate the clinical efficacy of a birch pollen allergoid IT using seven preseasonal injections and to evaluate immunological parameters that might explain clinical findings. Methods Thirty-seven patients were included into the study and randomized to either a symptomatic treatment or allergoid IT plus symptomatic treatment. Patients were examined during the pre-IT season, at two extraseasonal visits both before and after IT and during the post-IT season. At each visit, nasal secretion samples were taken and analysed for levels of IL-4, IL-5 and IFN gamma. In addition, short-term birch-specific T-cell lines (TCLs) were cultured from peripheral blood mononuclear cells of 10 patients of the IT group, both before and after IT, and the ratios of lymphocyte subpopulations were determined. Cytokine production by TCLs (IL-4, IL-5, IFN gamma, IL-10) and proliferation of TCLs in response to stimulation with birch pollen allergen were measured. Results It was possible to evaluate 27 patients in accordance with the study protocol. Clinical symptoms and medication intake were reduced as a result of the IT as were nasal secretion levels of IL-5 (P=0.007). IFN gamma was increased in nasal secretions (P=0.01), while IL-4 was not measurable in most samples. No effect was found on proliferation of birch pollen-reactive TCLs, cytokine production by TCLs and the frequency and ratio of CD4(+) and CD8(bright) or CD45RA(+) and CD45RO(+) cells in peripheral blood (all P > 0.05). Conclusion Preseasonal IT with a birch pollen allergoid is clinically effective in allergic rhinitis and influences cytokine production in the nose, but does not modulate the measured responses of peripheral blood T cells.