Molecular and Cellular Mechanism in Rhinitis Allergic Patients Treated With GRAZAX®

Inclusion Criteria: * Written informed consent obtained before entering the trial. * Male and female 18-65 years of age. * A clinical history of relevant rhinitis or rhinoconjunctivitis (with/without concurrent asthma) to grass pollen of at least one year prior to trial entry. * Documented positive specific IgE against grass pollen (IgE ≥ Class 2) into the 5 previous years. * Positive Skin Prick Test response (wheal diameter ≥ 3 mm) to Phleum pratense. * Negative pregnancy test for childbearing potential females. * Willing and able to comply with the trial protocol regimen. Exclusion Criteria: * Previous treatment by immunotherapy with grass allergen extracts. * A clinical history of symptomatic perennial allergic rhinitis or asthma. * Patients with contraindications for immunotherapy as established by the IT subcommittee of the EAACI or in the Summary of Products Characteristics of GRAZAX®. * Positive pregnancy test (in fertile females). * Being immediate family of the investigator or trial staff. * A mental condition rendering the subject unable to understand the nature, scope and possible consequences of the trial, and/or evidence of an uncooperative attitude. * Unlikely to be able to complete the trial, for any reason, or likely to move, or travel for extended periods of time during the trial period. * Use of an investigational drug within 30 days or 5 half-lives, whichever is longest, prior to screening.