Effect of Clopidogrel on Allergen Challenge in Asthma

Inclusion Criteria: * Confirmed diagnosis of asthma * Step one of treatment by GINA (2006) guidelines * baseline FEV1 \>80% predicted Exclusion Criteria: * current smoker * ex smoker who quit \<1 year prior to study and pack history \>10 pack years * current use of aspirin or other anticoagulant medication * Diagnosis or documented history of bronchopulmonary aspergillosis or uncontrolled infections * Any clinically significant cardiopulmonary abnormalities not related to pre-existing asthma * Past or present tuberculosis, systemic lupus erythematosis or multiple sclerosis * Any clinically significant neurological, renal, endocrine, gastrointestinal, hepatic or haematological abnormalities uncontrolled with standard treatment * History of psychiatric, medical or surgical disorders that may interfere with study * Clinical history suggestive of respiratory infection in month preceding study * Alcohol or recreational drug abuse * Diagnosis of immunodeficiency requiring treatment * Treatment with immunomodulators (inhaled corticosteroids in two months or oral corticosteroids in six months prior to study) * Ongoing allergen desensitisation therapy * Regular use of sedatives, hypnotics, tranquillisers * Positive hepatitis viral antigens or antibodies * Blood donation within 3 months of the study * Live immunisation \<4 wks prior to study * Inability to understand directions for study assessment * Inability to be contacted in case of emergency * Participation in another study at the same time or within a prior 3-month period