Costimulation Inhibition in Asthma

This study is designed to determine if treatment with abatacept is effective in decreasing
allergic airway inflammation in mild, atopic asthmatics. Subjects will be recruited from
the greater St Louis Metropolitan area. Eligible individuals will undergo a titrated skin
prick test. Following baseline evaluation, fiberoptic bronchoscopy with segmental allergen
challenge (SAC) will be performed. The subjects will be randomized to either placebo or
abatacept. After 12 weeks of study drug, the subjects will undergo repeat SAC. The primary
endpoint will be to determine if treatment with abatacept results in a 50% or greater
decrease in the percentage of eosinophils recovered in the bronchoalveolar lavage (BAL)
fluid following SAC as compared to placebo control. Secondary endpoints include measures of
airway obstruction and hyperreactivity, airway inflammation and symptoms as well as
determination of the safety of abatacept administration in this subject population.