The purpose of this study is to develop and characterize immunological assays on blood samples.

This is a clinical study in which there is no vaccine administered. It is designed for research purposes such as developing 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).

SAEs related to study participation/concurrent GSK medication/vaccine reporting was done at Day 0