Study in Allergic Adults to Support the Development of Immunological Assays

Inclusion Criteria: * Subjects who the investigator believes can and will comply with the requirements of the protocol. * Written informed consent obtained from the subject. * Healthy subjects (except the condition studied in the ALLERGY group). * A male or female between, and including 18 and 45 years of age at the time of study start. * Subject presenting moderate to severe clinical symptoms of allergy within the week before enrolment (only for ALLERGY group). * Subjects suffering from seasonal allergy to birch pollen previously documented by a medical history (only for ALLERGY group). * A positive skin prick test response realised and/or a positive test for specific IgE against birch within the last 5 years (only for ALLERGY group). Exclusion Criteria: * Any known or clinical signs of anaemia or any condition that would preclude the drawing of blood as described in the protocol. * Receipt of blood products 120 days prior to study visit. * Receipt of immunoglobulin 120 days prior to study visit. * Use of any investigational or non-registered product within 30 days preceding the study visit. * Concurrently participating in another clinical study, at the time of the study visit, in which the subject has been or will be exposed to an investigational or a non-investigational product. * Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history. * Any confirmed or suspected autoimmune or inflammatory disorders. * Administration of systemic or inhaled anti-inflammatory medications and, in particular, inhaled corticoid-steroids and cromoglycates within 30 days preceding the study visit. Purely local medications such as intranasal steroids or systemic symptomatic medications such as antihistamines and beta agonists are allowed. * Chronic administration of immunosuppressants or other immune-modifying drugs within six months prior to the study visit. * Pregnant or lactating female. * Any past or current birch-specific immunotherapy (only for ALLERGY group). * Any allergic disease as established by medical history before study start (only for CONTROL group). * Family history of allergic diseases in the first degree family members (only for CONTROL group).