This is the first proof of concept study for OC000459 and is undertaken to assess the effects of the compound on the development of inflammatory cytokines in a model (nasal allergen challenge model) that is validated and clinically safe and easy to conduct. OC000459 will be compared with placebo in the study.

The study will be a randomised, double blind, placebo controlled, crossover evaluation of the effect of OC000459 on cytokine secretion induced by nasal allergen challenge. Male subjects with a known history of allergic rhinitis and screening positive to allergen will be included. After dosing with OC000459 or placebo, nasal allergen challenge will be performed and measurements made in the nasal fluids. Nasal symptom scores will also be recorded. Safety parameters will be monitored throughout.

Inclusion Criteria:

1. Males aged 18 to 50 years with a history of symptoms of grass pollen related allergic rhinitis within the previous two years.

Exclusion Criteria:

1. Medical conditions likely to affect the outcome of the study.

2 History of immunotherapy in the past 3 years or currently on an immunotherapy treatment course including inhaled or local corticosteroids in the past 28 days.

3. Any infirmity, disability, or geographic location which, in the opinion of the principal investigator, would limit compliance with the protocol.