The study will evaluate the dose response of immunotherapy against grass pollen allergy using the recombinant grass pollen vaccine BM32. Efficacy will be analyzed by:

• skin prick testing
• grass pollen inhalation challenge
• antibody responses. In addition, the safety of subcutaneous application of BM32 will be evaluated.

Inclusion Criteria:

• History of seasonal allergic rhinitis from grass pollen
• Normal electrocardiogram
• Moderate to severe response to approx. 1500 grass pollen grains/m3 after 2 hrs of exposure in challenge chamber
• Positive skin prick test for grass pollen at or within 12 months preceding screening visit
• Positive RAST (class 2 or higher) for timothy grass pollen and to rPhl p 1 + rPhl p 5 at or within 12 months preceding screening visit

Exclusion Criteria:

• Pregnant or lactating females
• Females with childbearing potential not using medically acceptable birth control
• Structural nasal abnormalities, nasal polyposis, history of frequent nosebleeds, recent nasal surgery or ongoing upper respiratory tract infection
• Any respiratory disease other than mild asthma controlled with occasional short acting beta agonists and normal lung function
• Current or recent participation in another clinical trial
• SIT for grass pollen allergy in the last two years prior to study
• Past or present disease, which may affect outcome of the trial, judged by investigator
• Autoimmune diseases, immune defects including immunosuppression, immune- complex immunopathies
• Suspected hypersensitivity to any ingredients of study medication
• Use of prohibited medication prior to screening and throughout study
• depot corticosteroids (12 weeks)
• oral corticosteroids (8 weeks)
• inhaled corticosteroids (4 weeks)
• Allergic symptoms at the time of screening