The purpose of this study is to determine if Xolair can reduce the abnormal increase in limitation to airflow in patients with asthma in a relatively short time period. Another purpose is to determine if Xolair will decrease the amount of inflammation in the lungs of an asthmatic patient in the same time period.

Xolair, a recombinant humanized monoclonal anti-IgE antibody, has been studied extensively and proven efficacious in the treatment of asthma and other allergic disorders. In moderate to severe allergic asthmatic patients, Xolair reduced asthma exacerbations and improved symptoms. However, there is limited data on the effects of Xolair on airway hyperreactivity, an important component of asthma.

Inclusion Criteria:

• Female patients must have a negative urine pregnancy test at Visit 1 and a negative urine pregnancy test at subsequent visits. In addition, female patients must be using a medically acceptable form of birth control.
• History of mild to moderate asthma
• A positive skin prick test to one or more perennial environmental allergens (dog, cat, dermatophagoides farinae, or dermatophagoides pteronyssinus)
• A PC20 value for methacholine < 5 mg/mL
• A PC15 value for hypertonic saline at < 4 minutes
• Capable of faithfully attending regularly scheduled study visits
• Willing to avoid prohibited medications for the periods indicated in the protocol
• A baseline serum IgE level of > 30 IU/mL and < 700 IU/mL

Exclusion Criteria:

• Women of childbearing potential not using a medically acceptable form of birth control, as well as women who are breastfeeding
• Known sensitivity to study drug or class of study drug
• Any sinus, middle ear, oropharyngeal, upper or lower respiratory tract infection that has not resolved at least 2 weeks prior to the screening visit, or for which antibiotic therapy has not been completed at least 2 weeks prior to the screening visit
• Patients with a history of severe anaphylactoid or anaphylactic reactions
• Patients taking beta-adrenergic antagonists in any form
• Patients previously exposed to Xolair
• Patients with a known hypersensitivity to trial drug excipient ingredients or related drugs
• Chronic or intermittent use of inhaled, oral, intranasal, intramuscular, or intravenous corticosteroids, or use of topical corticosteroids other than intermittent use of low potency preparations
• Use of immunosuppressive medications
• History or presence of significant renal, hepatic, neurologic, cardiovascular, hematologic, metabolic, cerebrovascular, respiratory, gastrointestinal, or other significant medical condition, including autoimmune or collagen vascular disorders aside from organ-specific autoimmune disease limited to the thyroid that in the investigator's opinion could interfere with the study or require medical treatment that would interfere with the study