Allergen Challenge Chamber Study With Single Dose Intranasal GSK1004723 Compared With Placebo

Inclusion Criteria: * Subject is healthy apart from seasonal allergic rhinitis, as determined by a physician. Can have mild asthma. * Male * Aged 18 - 65 * Weight 50kg+, BMI 19-32 kg/m2 * Exhibit response to Challenge Chamber and skin prick test. * Non-smoker * Capable of giving informed consent Exclusion Criteria: * No nasal structural abnornmality/polyposis, surgery, infection. * any respiratory disease, other than mild asthma or seasonal allergic rhinitis * participated in another clinical study within 30 days. * Subject has donated a unit of blood within 1 month * Use of prescription or non-prescription drugs, including vitamins and st john's wort within 7 days of trial. * History of sensitivty to drug * History of alcohol/drug abuse within 12 months. * Positive Hepatitis B antibody test * Positive HIV antibody test * Risk of non-compliance with study protocol * Perenial allergic rhinitis * Administration of oral, injectable or dermal corticosteriods within 8 weeks, intranasal or inhaled within 3 weeks. * Past or present disease that may affect outcome, as judge by investigator Specific Immunotherapy within 2 years