Molecular and Cellular Mechanism in the Course of Immunotherapy With a Phleum Pratense Oral Lyophilisate

Inclusion Criteria: * A history of grass pollen allergy * Positive skin prick test to grass * Positive specific IgE against Phl p 5 * Written informed consent before entering the trial. * Female subjects who are fertile must have a negative pregnancy test and be willing to practise appropriate contraceptive methods. * Subject willing and able to comply with the trial protocol. Exclusion Criteria: * Previous treatment by immunotherapy with grass allergen extracts. * Ongoing treatment with any allergen specific immunotherapy product. * Previous or ongoing treatment with Omalizumab, mono amine oxidase (MAO) inhibitors or tricyclic antidepressant medication. * Use of medication at the screening visit which can interfere with SPT results * A clinical history of symptomatic perennial allergic rhinitis or asthma. * History of allergy, hypersensitivity or intolerance to the excipients of IMP (except for Phleum pratense). * Systemic disease affecting the immune system (e.g. autoimmune disease, immune complex disease, or immune deficiency disease). * Any clinically relevant chronic disease (≥ 3 months duration) (e.g. cystic fibrosis, malignancy, type I diabetes mellitus, malabsorption or malnutrition, renal or hepatic insufficiency). * Inflammatory conditions in the oral cavity with severe symptoms such as oral lichen planus with ulcerations or severe oral mycosis at randomisation. * FEV1 ≤ 70% of predicted value. * Symptoms of or treatment for upper respiratory tract infection, acu…