Clinical, functional, and immunologic effects of sublingual immunotherapy in birch pollinosis: a 3-year randomized...

Sublingual immunotherapy (SLIT) has been proved effective in allergic rhinitis, but there are few studies assessing its effects on inflammation and on the lower airways.

We sought to evaluate at the same time the effects of SLIT on rhinitis symptoms, nasal inflammation, and lower airways function in patients with birch pollinosis.

Adult patients with rhinitis and asthma monosensitized to birch were evaluated during a run-in pollen season and then randomized to receive openly either drugs alone or drugs plus SLIT and reevaluated in the subsequent 4 pollen seasons. Rhinitis symptoms and consumption of bronchodilators were assessed by means of diary card. A nasal smear for eosinophil count was carried out in and out of pollen seasons, and pulmonary function tests with methacholine challenge were performed at each season.

Of 79 enrolled patients, 27 dropped out, with a significantly higher rate of dropouts in the control group. There was a decrease in symptoms and bronchodilator use in the SLIT group versus the control group, becoming significant at the second and third pollen seasons, respectively ( P < .01 at all times). Nasal eosinophils decreased significantly in the active group, starting from the third pollen season ( P < .01). In the SLIT group a significant increase in FEV 1 , specific airways conductance, and maximal expiratory flow at 25% of forced vital capacity was seen starting from the second year and was associated with an increase in the methacholine threshold dose ( P < .01). The differences were significant also at the intragroup comparison over time.

SLIT achieved a significant clinical benefit in birch pollinosis, reduced the eosinophil infiltration in nasal mucosa, and significantly improved pulmonary function during the pollen seasons.