Allergen-specific immunotherapy (SIT), the administration of gradually increasing quantities of an allergen extract to an allergic patient, is a curative approach which directly treats the underlying allergic disease. GrassMATAMPL has been developed to provide pre-seasonal specific immunotherapy for patients with an allergy to grass pollen (hay fever). The purpose of this double-blind Phase IIb study is to assess the tolerability and immunogenicity of different doses of GrassMATAMPL in volunteers allergic to grasses and rye pollen.

Inclusion Criteria:

• positive skin prick test for grass and rye allergen
• Specific IgE for grass and rye as documented by radioallergosorbent or equivalent test with class >= 2
• History of at least 1 season of moderate to severe seasonal rhinoconjunctivitis due to an IgE - mediated allergy to pollen from grass and rye
• Males or non-pregnant, non-lactating females who are post-menopausal or naturally or surgically sterile. Females of childbearing potential have a confirmed absence of pregnancy according to a negative urine pregnancy test and must be using an acceptable birth control method.
• Spirometry at Screening demonstrates FEV1 >= 80% predicted and FEV1/FVC >= 70%

Exclusion Criteria:

• Acute or subacute atopic dermatitis and/or urticaria factitia and/or urticaria due to physical or chemical influence and/or chronic dermatitis
• Patient has moderate to severe asthma
• Visual inspection of the forearms indicates potential problems with the conduct or interpretation of the skin prick test; both forearms must be available for testing
• History or presence of diabetes, cancer or any clinically significant cardiac, metabolic renal, hematologic diseases or disorders
• Recent clinically significant history (within 2 years) of hepatic gastrointestinal, dermatologic, venereal, neurologic or psychiatric diseases or disorders
• Any clinically significant (as determined by the investigator) abnormal laboratory value
• Perennial allergens: clinically relevant sensitivity against house dust mites, molds, and epithelia
• Patient has clinically relevant sensitivity against the following summer/autumn season flowering plants: plantain, orache, nettle, mugwort, Bermuda grass, or ragweed.
• Secondary alteration at the affected organ
• History of autoimmune diseases and/or rheumatoid diseases
• Patient is taking b-blockers
• Patient who is not allowed to receive adrenalin
• Patients in whom tyrosine metabolism is disturbed
• Presence of a disease with a pathogenesis interfering with the immune response and patient has received medication which could influence the results of this study
• Documented evidence of acute or significant chronic infection
• History of anaphylaxis
• Documented history of angioedema
• Hypersensitivity to excipients in the study medications
• Previous or current immunotherapy with comparable grass/rye allergen extracts
• Currently using anti-allergy medication and other drugs with antihistaminic activity
• Patients currently participating in a clinical trial or who have been exposed to study medication within the last 30 days
• Patient is pregnant or planning pregnancy and/or lactating
• Patient has received treatment with preparation containing MPL® during the past 12 months
• Any systemic disorder that could interfere with the evaluation of the study medication(s)
• Clinical history of drug or alcohol abuse that would interfere with the patient's participation in the study