Subjects will receive an albuterol inhaler to use as needed for immediate relief of symptoms and fluticasone 250 mcg/salmeterol 50 mcg or fluticasone 500 mcg/salmeterol 50 mcg (Advair Diskus® 250/50 or 500/50) to be taken twice daily. At certain visits, they will be given Xolair® injections followed by various assessments, including CT scans and lung function tests.