Local nasal immunotherapy for birch allergic rhinitis with extract in powder form

Traditional subcutaneous immunotherapy has been proved effective in birch pollenosis. It has, however, some drawbacks as systemic reactions, which are rare but important. Local nasal immunotherapy (LNIT) represents a potential safer route of allergen administration.

To study the clinical efficacy and safety of local nasal immunotherapy by means of an extract in powder form as treatment of birch allergic rhinitis.

Thirty birch allergic patients have been selected on the basis of a positive history, skin test, radioallergosorbent test assay (RAST) and specific nasal challenge. Two 15 patient groups were randomly assigned to the active treatment or to the placebo one. Treatment lasted 22 weeks (14 for the build-up phase and eight for maintenance period) and symptoms were recorded during the treatment and the birch pollen season.

The clinical efficacy of LNIT is suggested by a significant reduction of medication score only in the treated group during the pollen season, although the symptom score was significantly lower in the treated group for 1 week only. Moreover, a significant increase of specific nasal threshold dose was observed after treatment only in the active treated group. Mild adverse reaction to LNIT, limited to the upper respiratory tract, were reported during the treatment in the active group, but they did not interfere with LNIT schedule. No asthmatic or systemic reaction were observed.

This study indicates that LNIT with allergen in powder form has proven clinically effective in the treatment of birch allergic rhinitis. Further studies are needed to establish whether this treatment can be considered a real alternative to the traditional subcutaneous immunotherapy in birch allergic rhinitis.