Ellis AK, et al. - Grastek is a standardized sublingual immunotherapy tablet(SLIT-T) approved for the treatment of grass pollen-induced allergic rhinitis(AR) and conjunctivitis. Herein, the treatment impact of Grastek for birch pollen-induced AR was assessed in participants sensitized to both grass and birch pollen using the Environmental Exposure Unit(EEU). Findings demonstrated no by-stander effect of grass SLIT-T on birch pollen-induced AR symptoms. It was also observed that grass SLIT-T-induced symptomatic benefits were likely allergen specific.