Effect of Xolair on Airway Hyperresponsiveness

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